diff --git a/docs/pages/release_notes.md b/docs/pages/release_notes.md
index 544d54f101..befd17d68d 100644
--- a/docs/pages/release_notes.md
+++ b/docs/pages/release_notes.md
@@ -151,9 +151,21 @@ in the Migration Guide.
 
 #### API Changes
 
-**Moved classes**
+**Moved classes/consolidated packages**
 * pmd-core
-  * The interface {%jdoc core::rule.Rule %} has been moved into the new package {% jdoc_package core::rule %}.
+  * Many types have been moved from the base package `net.sourceforge.pmd` into the new subpackage {% jdoc_package core::rule %}
+    * {%jdoc core::rule.Rule %}
+    * {%jdoc core::rule.RuleFactory %} (moved from `net.sourceforge.pmd.rules`; it has now been hidden from public API)
+    * {%jdoc core::rule.RulePriority %}
+    * {%jdoc core::rule.RuleSet %}
+    * {%jdoc core::rule.RuleSetFactory %}
+    * {%jdoc core::rule.RuleSetFactoryCompatibility %}
+    * {%jdoc core::rule.RuleSetLoader %}
+    * {%jdoc core::rule.RuleSetLoadException %}
+    * {%jdoc core::rule.RuleSetReference %} (note: this is _not_ public API)
+    * {%jdoc core::rule.RuleSetReferenceId %} (has been hidden from public API)
+    * {%jdoc core::rule.RuleSets %} (note: this is _not_ public API)
+    * {%jdoc core::rule.RuleSetWriter %}
 
 **Removed classes and methods**
 
diff --git a/pmd-ant/src/main/java/net/sourceforge/pmd/ant/PMDTask.java b/pmd-ant/src/main/java/net/sourceforge/pmd/ant/PMDTask.java
index db10833ff7..215f2929f0 100644
--- a/pmd-ant/src/main/java/net/sourceforge/pmd/ant/PMDTask.java
+++ b/pmd-ant/src/main/java/net/sourceforge/pmd/ant/PMDTask.java
@@ -17,9 +17,9 @@ import org.apache.tools.ant.types.Path;
 import org.apache.tools.ant.types.Reference;
 import org.apache.tools.ant.types.Resource;
 
-import net.sourceforge.pmd.RulePriority;
 import net.sourceforge.pmd.annotation.InternalApi;
 import net.sourceforge.pmd.ant.internal.PMDTaskImpl;
+import net.sourceforge.pmd.rule.RulePriority;
 
 /**
  * PMD Ant task. Setters of this class are interpreted by Ant as properties
diff --git a/pmd-ant/src/main/java/net/sourceforge/pmd/ant/internal/PMDTaskImpl.java b/pmd-ant/src/main/java/net/sourceforge/pmd/ant/internal/PMDTaskImpl.java
index 3bd399fc64..1f48d23553 100644
--- a/pmd-ant/src/main/java/net/sourceforge/pmd/ant/internal/PMDTaskImpl.java
+++ b/pmd-ant/src/main/java/net/sourceforge/pmd/ant/internal/PMDTaskImpl.java
@@ -23,8 +23,6 @@ import org.slf4j.event.Level;
 
 import net.sourceforge.pmd.PMDConfiguration;
 import net.sourceforge.pmd.PmdAnalysis;
-import net.sourceforge.pmd.RulePriority;
-import net.sourceforge.pmd.RuleSetLoader;
 import net.sourceforge.pmd.ant.Formatter;
 import net.sourceforge.pmd.ant.PMDTask;
 import net.sourceforge.pmd.ant.SourceLanguage;
@@ -39,6 +37,8 @@ import net.sourceforge.pmd.reporting.FileAnalysisListener;
 import net.sourceforge.pmd.reporting.GlobalAnalysisListener;
 import net.sourceforge.pmd.reporting.ReportStats;
 import net.sourceforge.pmd.reporting.ReportStatsListener;
+import net.sourceforge.pmd.rule.RulePriority;
+import net.sourceforge.pmd.rule.RuleSetLoader;
 
 public class PMDTaskImpl {
 
diff --git a/pmd-apex/src/test/java/net/sourceforge/pmd/lang/apex/DefaultRulesetTest.java b/pmd-apex/src/test/java/net/sourceforge/pmd/lang/apex/DefaultRulesetTest.java
index 3ca9685389..f2b360cba9 100644
--- a/pmd-apex/src/test/java/net/sourceforge/pmd/lang/apex/DefaultRulesetTest.java
+++ b/pmd-apex/src/test/java/net/sourceforge/pmd/lang/apex/DefaultRulesetTest.java
@@ -9,9 +9,9 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import org.junit.jupiter.api.Test;
 
-import net.sourceforge.pmd.AbstractRuleSetFactoryTest;
-import net.sourceforge.pmd.RuleSet;
-import net.sourceforge.pmd.RuleSetLoader;
+import net.sourceforge.pmd.rule.AbstractRuleSetFactoryTest;
+import net.sourceforge.pmd.rule.RuleSet;
+import net.sourceforge.pmd.rule.RuleSetLoader;
 
 import com.github.stefanbirkner.systemlambda.SystemLambda;
 
diff --git a/pmd-apex/src/test/java/net/sourceforge/pmd/lang/apex/RuleSetFactoryTest.java b/pmd-apex/src/test/java/net/sourceforge/pmd/lang/apex/RuleSetFactoryTest.java
index fb955369af..38383cb831 100644
--- a/pmd-apex/src/test/java/net/sourceforge/pmd/lang/apex/RuleSetFactoryTest.java
+++ b/pmd-apex/src/test/java/net/sourceforge/pmd/lang/apex/RuleSetFactoryTest.java
@@ -4,7 +4,7 @@
 
 package net.sourceforge.pmd.lang.apex;
 
-import net.sourceforge.pmd.AbstractRuleSetFactoryTest;
+import net.sourceforge.pmd.rule.AbstractRuleSetFactoryTest;
 
 class RuleSetFactoryTest extends AbstractRuleSetFactoryTest {
     // no additional tests yet
diff --git a/pmd-apex/src/test/java/net/sourceforge/pmd/lang/apex/rule/design/UnusedMethodTest.java b/pmd-apex/src/test/java/net/sourceforge/pmd/lang/apex/rule/design/UnusedMethodTest.java
index c64c4158db..f6d18cf2da 100644
--- a/pmd-apex/src/test/java/net/sourceforge/pmd/lang/apex/rule/design/UnusedMethodTest.java
+++ b/pmd-apex/src/test/java/net/sourceforge/pmd/lang/apex/rule/design/UnusedMethodTest.java
@@ -16,8 +16,6 @@ import org.junit.jupiter.api.io.TempDir;
 import net.sourceforge.pmd.PMDConfiguration;
 import net.sourceforge.pmd.PmdAnalysis;
 import net.sourceforge.pmd.Report;
-import net.sourceforge.pmd.RuleSet;
-import net.sourceforge.pmd.RuleSetLoader;
 import net.sourceforge.pmd.RuleViolation;
 import net.sourceforge.pmd.lang.Language;
 import net.sourceforge.pmd.lang.LanguageVersion;
@@ -25,6 +23,8 @@ import net.sourceforge.pmd.lang.apex.ApexLanguageModule;
 import net.sourceforge.pmd.lang.apex.ApexLanguageProperties;
 import net.sourceforge.pmd.reporting.GlobalAnalysisListener;
 import net.sourceforge.pmd.rule.Rule;
+import net.sourceforge.pmd.rule.RuleSet;
+import net.sourceforge.pmd.rule.RuleSetLoader;
 
 import com.nawforce.pkgforce.path.PathFactory;
 import com.nawforce.pkgforce.path.PathLike;
diff --git a/pmd-cli/src/main/java/net/sourceforge/pmd/cli/commands/internal/PmdCommand.java b/pmd-cli/src/main/java/net/sourceforge/pmd/cli/commands/internal/PmdCommand.java
index 29758b74be..4536ad05c0 100644
--- a/pmd-cli/src/main/java/net/sourceforge/pmd/cli/commands/internal/PmdCommand.java
+++ b/pmd-cli/src/main/java/net/sourceforge/pmd/cli/commands/internal/PmdCommand.java
@@ -20,7 +20,6 @@ import org.slf4j.LoggerFactory;
 
 import net.sourceforge.pmd.PMDConfiguration;
 import net.sourceforge.pmd.PmdAnalysis;
-import net.sourceforge.pmd.RulePriority;
 import net.sourceforge.pmd.benchmark.TextTimingReportRenderer;
 import net.sourceforge.pmd.benchmark.TimeTracker;
 import net.sourceforge.pmd.benchmark.TimingReport;
@@ -37,6 +36,7 @@ import net.sourceforge.pmd.properties.PropertyDescriptor;
 import net.sourceforge.pmd.renderers.Renderer;
 import net.sourceforge.pmd.renderers.RendererFactory;
 import net.sourceforge.pmd.reporting.ReportStats;
+import net.sourceforge.pmd.rule.RulePriority;
 import net.sourceforge.pmd.util.StringUtil;
 import net.sourceforge.pmd.util.log.MessageReporter;
 import net.sourceforge.pmd.util.log.internal.SimpleMessageReporter;
diff --git a/pmd-cli/src/main/java/net/sourceforge/pmd/cli/commands/typesupport/internal/RulePriorityTypeSupport.java b/pmd-cli/src/main/java/net/sourceforge/pmd/cli/commands/typesupport/internal/RulePriorityTypeSupport.java
index 48ee080be9..82660c26be 100644
--- a/pmd-cli/src/main/java/net/sourceforge/pmd/cli/commands/typesupport/internal/RulePriorityTypeSupport.java
+++ b/pmd-cli/src/main/java/net/sourceforge/pmd/cli/commands/typesupport/internal/RulePriorityTypeSupport.java
@@ -8,7 +8,7 @@ import java.util.ArrayList;
 import java.util.Iterator;
 import java.util.List;
 
-import net.sourceforge.pmd.RulePriority;
+import net.sourceforge.pmd.rule.RulePriority;
 
 import picocli.CommandLine.ITypeConverter;
 import picocli.CommandLine.TypeConversionException;
diff --git a/pmd-compat6/src/main/java/net/sourceforge/pmd/PMDConfiguration.java b/pmd-compat6/src/main/java/net/sourceforge/pmd/PMDConfiguration.java
index 87175d7405..90954321a7 100644
--- a/pmd-compat6/src/main/java/net/sourceforge/pmd/PMDConfiguration.java
+++ b/pmd-compat6/src/main/java/net/sourceforge/pmd/PMDConfiguration.java
@@ -32,6 +32,8 @@ import net.sourceforge.pmd.lang.Language;
 import net.sourceforge.pmd.lang.LanguageRegistry;
 import net.sourceforge.pmd.renderers.Renderer;
 import net.sourceforge.pmd.renderers.RendererFactory;
+import net.sourceforge.pmd.rule.RulePriority;
+import net.sourceforge.pmd.rule.RuleSetLoader;
 import net.sourceforge.pmd.util.AssertionUtil;
 import net.sourceforge.pmd.util.log.internal.SimpleMessageReporter;
 
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/PMDConfiguration.java b/pmd-core/src/main/java/net/sourceforge/pmd/PMDConfiguration.java
index b262878dfe..8eaa7de870 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/PMDConfiguration.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/PMDConfiguration.java
@@ -29,6 +29,8 @@ import net.sourceforge.pmd.lang.Language;
 import net.sourceforge.pmd.lang.LanguageRegistry;
 import net.sourceforge.pmd.renderers.Renderer;
 import net.sourceforge.pmd.renderers.RendererFactory;
+import net.sourceforge.pmd.rule.RulePriority;
+import net.sourceforge.pmd.rule.RuleSetLoader;
 import net.sourceforge.pmd.util.AssertionUtil;
 import net.sourceforge.pmd.util.log.internal.SimpleMessageReporter;
 
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/PmdAnalysis.java b/pmd-core/src/main/java/net/sourceforge/pmd/PmdAnalysis.java
index 5293246812..23bac0ab59 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/PmdAnalysis.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/PmdAnalysis.java
@@ -50,6 +50,9 @@ import net.sourceforge.pmd.reporting.ListenerInitializer;
 import net.sourceforge.pmd.reporting.ReportStats;
 import net.sourceforge.pmd.reporting.ReportStatsListener;
 import net.sourceforge.pmd.rule.Rule;
+import net.sourceforge.pmd.rule.RuleSet;
+import net.sourceforge.pmd.rule.RuleSetLoader;
+import net.sourceforge.pmd.rule.RuleSets;
 import net.sourceforge.pmd.util.AssertionUtil;
 import net.sourceforge.pmd.util.StringUtil;
 import net.sourceforge.pmd.util.log.MessageReporter;
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/cache/AbstractAnalysisCache.java b/pmd-core/src/main/java/net/sourceforge/pmd/cache/AbstractAnalysisCache.java
index 7a8b7a9498..21904f6756 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/cache/AbstractAnalysisCache.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/cache/AbstractAnalysisCache.java
@@ -27,7 +27,6 @@ import org.slf4j.LoggerFactory;
 
 import net.sourceforge.pmd.PMDVersion;
 import net.sourceforge.pmd.Report.ProcessingError;
-import net.sourceforge.pmd.RuleSets;
 import net.sourceforge.pmd.RuleViolation;
 import net.sourceforge.pmd.annotation.InternalApi;
 import net.sourceforge.pmd.benchmark.TimeTracker;
@@ -39,6 +38,7 @@ import net.sourceforge.pmd.lang.document.FileId;
 import net.sourceforge.pmd.lang.document.TextDocument;
 import net.sourceforge.pmd.lang.document.TextFile;
 import net.sourceforge.pmd.reporting.FileAnalysisListener;
+import net.sourceforge.pmd.rule.RuleSets;
 
 /**
  * Abstract implementation of the analysis cache. Handles all operations, except for persistence.
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/cache/AnalysisCache.java b/pmd-core/src/main/java/net/sourceforge/pmd/cache/AnalysisCache.java
index 2b7e0e1b5a..4eaf19bb27 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/cache/AnalysisCache.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/cache/AnalysisCache.java
@@ -8,13 +8,13 @@ import java.io.IOException;
 import java.util.Collection;
 import java.util.List;
 
-import net.sourceforge.pmd.RuleSets;
 import net.sourceforge.pmd.RuleViolation;
 import net.sourceforge.pmd.annotation.InternalApi;
 import net.sourceforge.pmd.lang.document.TextDocument;
 import net.sourceforge.pmd.lang.document.TextFile;
 import net.sourceforge.pmd.reporting.FileAnalysisListener;
 import net.sourceforge.pmd.reporting.GlobalAnalysisListener;
+import net.sourceforge.pmd.rule.RuleSets;
 
 /**
  * An analysis cache for incremental analysis.
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/cache/AnalysisCacheListener.java b/pmd-core/src/main/java/net/sourceforge/pmd/cache/AnalysisCacheListener.java
index 702631244c..af16b0c944 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/cache/AnalysisCacheListener.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/cache/AnalysisCacheListener.java
@@ -7,11 +7,11 @@ package net.sourceforge.pmd.cache;
 import java.io.IOException;
 import java.util.Collection;
 
-import net.sourceforge.pmd.RuleSets;
 import net.sourceforge.pmd.annotation.InternalApi;
 import net.sourceforge.pmd.lang.document.TextFile;
 import net.sourceforge.pmd.reporting.FileAnalysisListener;
 import net.sourceforge.pmd.reporting.GlobalAnalysisListener;
+import net.sourceforge.pmd.rule.RuleSets;
 
 /**
  * Adapter to wrap {@link AnalysisCache} behaviour in a {@link GlobalAnalysisListener}.
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/cache/CachedRuleMapper.java b/pmd-core/src/main/java/net/sourceforge/pmd/cache/CachedRuleMapper.java
index 31c41174eb..456abfade1 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/cache/CachedRuleMapper.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/cache/CachedRuleMapper.java
@@ -7,9 +7,9 @@ package net.sourceforge.pmd.cache;
 import java.util.HashMap;
 import java.util.Map;
 
-import net.sourceforge.pmd.RuleSets;
 import net.sourceforge.pmd.annotation.InternalApi;
 import net.sourceforge.pmd.rule.Rule;
+import net.sourceforge.pmd.rule.RuleSets;
 
 /**
  * A mapper from rule class names to rule instances for cached rules.
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/cache/FileAnalysisCache.java b/pmd-core/src/main/java/net/sourceforge/pmd/cache/FileAnalysisCache.java
index b1fcc12ed0..2e2eb73a3c 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/cache/FileAnalysisCache.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/cache/FileAnalysisCache.java
@@ -19,7 +19,6 @@ import java.util.Map;
 import java.util.stream.Collectors;
 
 import net.sourceforge.pmd.PMDVersion;
-import net.sourceforge.pmd.RuleSets;
 import net.sourceforge.pmd.RuleViolation;
 import net.sourceforge.pmd.annotation.InternalApi;
 import net.sourceforge.pmd.benchmark.TimeTracker;
@@ -27,6 +26,7 @@ import net.sourceforge.pmd.benchmark.TimedOperation;
 import net.sourceforge.pmd.benchmark.TimedOperationCategory;
 import net.sourceforge.pmd.lang.document.FileId;
 import net.sourceforge.pmd.lang.document.TextFile;
+import net.sourceforge.pmd.rule.RuleSets;
 
 /**
  * An analysis cache backed by a regular file.
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/cache/NoopAnalysisCache.java b/pmd-core/src/main/java/net/sourceforge/pmd/cache/NoopAnalysisCache.java
index ea8896501d..005e408616 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/cache/NoopAnalysisCache.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/cache/NoopAnalysisCache.java
@@ -8,12 +8,12 @@ import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
 
-import net.sourceforge.pmd.RuleSets;
 import net.sourceforge.pmd.RuleViolation;
 import net.sourceforge.pmd.annotation.InternalApi;
 import net.sourceforge.pmd.lang.document.TextDocument;
 import net.sourceforge.pmd.lang.document.TextFile;
 import net.sourceforge.pmd.reporting.FileAnalysisListener;
+import net.sourceforge.pmd.rule.RuleSets;
 
 /**
  * A NOOP analysis cache. Easier / safer than null-checking.
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/lang/LanguageProcessor.java b/pmd-core/src/main/java/net/sourceforge/pmd/lang/LanguageProcessor.java
index ccdc14248d..68e6f1de86 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/lang/LanguageProcessor.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/lang/LanguageProcessor.java
@@ -9,11 +9,11 @@ import java.util.List;
 
 import org.checkerframework.checker.nullness.qual.NonNull;
 
-import net.sourceforge.pmd.RuleSets;
 import net.sourceforge.pmd.annotation.InternalApi;
 import net.sourceforge.pmd.cache.AnalysisCache;
 import net.sourceforge.pmd.lang.document.TextFile;
 import net.sourceforge.pmd.reporting.GlobalAnalysisListener;
+import net.sourceforge.pmd.rule.RuleSets;
 import net.sourceforge.pmd.util.log.MessageReporter;
 
 /**
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/lang/impl/MonoThreadProcessor.java b/pmd-core/src/main/java/net/sourceforge/pmd/lang/impl/MonoThreadProcessor.java
index fe26c289f6..72315336c8 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/lang/impl/MonoThreadProcessor.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/lang/impl/MonoThreadProcessor.java
@@ -4,9 +4,9 @@
 
 package net.sourceforge.pmd.lang.impl;
 
-import net.sourceforge.pmd.RuleSets;
 import net.sourceforge.pmd.lang.LanguageProcessor.AnalysisTask;
 import net.sourceforge.pmd.lang.document.TextFile;
+import net.sourceforge.pmd.rule.RuleSets;
 
 /**
  * @author Romain Pelisse <belaran@gmail.com>
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/lang/impl/MultiThreadProcessor.java b/pmd-core/src/main/java/net/sourceforge/pmd/lang/impl/MultiThreadProcessor.java
index cd0e26dc37..c115d21415 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/lang/impl/MultiThreadProcessor.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/lang/impl/MultiThreadProcessor.java
@@ -12,9 +12,9 @@ import java.util.concurrent.Executors;
 import java.util.concurrent.Future;
 import java.util.concurrent.TimeUnit;
 
-import net.sourceforge.pmd.RuleSets;
 import net.sourceforge.pmd.lang.LanguageProcessor.AnalysisTask;
 import net.sourceforge.pmd.lang.document.TextFile;
+import net.sourceforge.pmd.rule.RuleSets;
 import net.sourceforge.pmd.util.log.MessageReporter;
 
 
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/lang/impl/PmdRunnable.java b/pmd-core/src/main/java/net/sourceforge/pmd/lang/impl/PmdRunnable.java
index 8059d94e2b..6c085cdfbd 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/lang/impl/PmdRunnable.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/lang/impl/PmdRunnable.java
@@ -10,7 +10,6 @@ import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
 import net.sourceforge.pmd.Report;
-import net.sourceforge.pmd.RuleSets;
 import net.sourceforge.pmd.RuleViolation;
 import net.sourceforge.pmd.benchmark.TimeTracker;
 import net.sourceforge.pmd.benchmark.TimedOperation;
@@ -29,6 +28,7 @@ import net.sourceforge.pmd.lang.ast.SemanticException;
 import net.sourceforge.pmd.lang.document.TextDocument;
 import net.sourceforge.pmd.lang.document.TextFile;
 import net.sourceforge.pmd.reporting.FileAnalysisListener;
+import net.sourceforge.pmd.rule.RuleSets;
 
 /**
  * A processing task for a single file.
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/lang/rule/AbstractDelegateRule.java b/pmd-core/src/main/java/net/sourceforge/pmd/lang/rule/AbstractDelegateRule.java
index a1b2386402..f3f11349e0 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/lang/rule/AbstractDelegateRule.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/lang/rule/AbstractDelegateRule.java
@@ -8,7 +8,6 @@ import java.util.List;
 import java.util.Map;
 
 import net.sourceforge.pmd.RuleContext;
-import net.sourceforge.pmd.RulePriority;
 import net.sourceforge.pmd.lang.Language;
 import net.sourceforge.pmd.lang.LanguageProcessor;
 import net.sourceforge.pmd.lang.LanguageVersion;
@@ -16,6 +15,7 @@ import net.sourceforge.pmd.lang.ast.Node;
 import net.sourceforge.pmd.properties.PropertyDescriptor;
 import net.sourceforge.pmd.properties.PropertySource;
 import net.sourceforge.pmd.rule.Rule;
+import net.sourceforge.pmd.rule.RulePriority;
 
 /**
  * Base class for Rule implementations which delegate to another Rule instance.
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/lang/rule/AbstractRule.java b/pmd-core/src/main/java/net/sourceforge/pmd/lang/rule/AbstractRule.java
index cf7db90d0b..081696930e 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/lang/rule/AbstractRule.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/lang/rule/AbstractRule.java
@@ -16,7 +16,6 @@ import java.util.Set;
 import org.checkerframework.checker.nullness.qual.NonNull;
 
 import net.sourceforge.pmd.RuleContext;
-import net.sourceforge.pmd.RulePriority;
 import net.sourceforge.pmd.lang.Language;
 import net.sourceforge.pmd.lang.LanguageVersion;
 import net.sourceforge.pmd.lang.ast.Node;
@@ -24,6 +23,7 @@ import net.sourceforge.pmd.lang.ast.RootNode;
 import net.sourceforge.pmd.properties.AbstractPropertySource;
 import net.sourceforge.pmd.properties.PropertyDescriptor;
 import net.sourceforge.pmd.rule.Rule;
+import net.sourceforge.pmd.rule.RulePriority;
 
 /**
  * Basic abstract implementation of all parser-independent methods of the Rule
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/lang/rule/RuleReference.java b/pmd-core/src/main/java/net/sourceforge/pmd/lang/rule/RuleReference.java
index a0f9b75734..374a26208d 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/lang/rule/RuleReference.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/lang/rule/RuleReference.java
@@ -12,11 +12,11 @@ import java.util.List;
 import java.util.Map;
 import java.util.Objects;
 
-import net.sourceforge.pmd.RulePriority;
-import net.sourceforge.pmd.RuleSetReference;
 import net.sourceforge.pmd.lang.LanguageVersion;
 import net.sourceforge.pmd.properties.PropertyDescriptor;
 import net.sourceforge.pmd.rule.Rule;
+import net.sourceforge.pmd.rule.RulePriority;
+import net.sourceforge.pmd.rule.RuleSetReference;
 import net.sourceforge.pmd.util.StringUtil;
 
 /**
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/lang/rule/internal/RuleApplicator.java b/pmd-core/src/main/java/net/sourceforge/pmd/lang/rule/internal/RuleApplicator.java
index a1b9f089fd..8036814d7a 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/lang/rule/internal/RuleApplicator.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/lang/rule/internal/RuleApplicator.java
@@ -13,7 +13,6 @@ import org.slf4j.LoggerFactory;
 
 import net.sourceforge.pmd.Report.ProcessingError;
 import net.sourceforge.pmd.RuleContext;
-import net.sourceforge.pmd.RuleSet;
 import net.sourceforge.pmd.benchmark.TimeTracker;
 import net.sourceforge.pmd.benchmark.TimedOperation;
 import net.sourceforge.pmd.benchmark.TimedOperationCategory;
@@ -23,6 +22,7 @@ import net.sourceforge.pmd.lang.ast.Node;
 import net.sourceforge.pmd.lang.ast.RootNode;
 import net.sourceforge.pmd.reporting.FileAnalysisListener;
 import net.sourceforge.pmd.rule.Rule;
+import net.sourceforge.pmd.rule.RuleSet;
 import net.sourceforge.pmd.util.AssertionUtil;
 import net.sourceforge.pmd.util.StringUtil;
 
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/properties/PropertyDescriptor.java b/pmd-core/src/main/java/net/sourceforge/pmd/properties/PropertyDescriptor.java
index 5bd40d48fb..a8c3d51264 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/properties/PropertyDescriptor.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/properties/PropertyDescriptor.java
@@ -8,8 +8,8 @@ import java.util.Objects;
 
 import org.checkerframework.checker.nullness.qual.Nullable;
 
-import net.sourceforge.pmd.RuleSetWriter;
 import net.sourceforge.pmd.annotation.InternalApi;
+import net.sourceforge.pmd.rule.RuleSetWriter;
 
 
 /**
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/rule/Rule.java b/pmd-core/src/main/java/net/sourceforge/pmd/rule/Rule.java
index 0a8fee6e5b..6d2ed5c65d 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/rule/Rule.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/rule/Rule.java
@@ -9,8 +9,6 @@ import java.util.Optional;
 import java.util.regex.Pattern;
 
 import net.sourceforge.pmd.RuleContext;
-import net.sourceforge.pmd.RulePriority;
-import net.sourceforge.pmd.RuleSet;
 import net.sourceforge.pmd.lang.Language;
 import net.sourceforge.pmd.lang.LanguageProcessor;
 import net.sourceforge.pmd.lang.LanguageVersion;
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/rules/RuleFactory.java b/pmd-core/src/main/java/net/sourceforge/pmd/rule/RuleFactory.java
similarity index 98%
rename from pmd-core/src/main/java/net/sourceforge/pmd/rules/RuleFactory.java
rename to pmd-core/src/main/java/net/sourceforge/pmd/rule/RuleFactory.java
index d918629299..4f15ad3420 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/rules/RuleFactory.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/rule/RuleFactory.java
@@ -2,7 +2,7 @@
  * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
  */
 
-package net.sourceforge.pmd.rules;
+package net.sourceforge.pmd.rule;
 
 import static net.sourceforge.pmd.util.internal.xml.SchemaConstants.CLASS;
 import static net.sourceforge.pmd.util.internal.xml.SchemaConstants.DELIMITER;
@@ -41,9 +41,6 @@ import org.w3c.dom.Attr;
 import org.w3c.dom.Element;
 import org.w3c.dom.Node;
 
-import net.sourceforge.pmd.RulePriority;
-import net.sourceforge.pmd.RuleSetReference;
-import net.sourceforge.pmd.annotation.InternalApi;
 import net.sourceforge.pmd.lang.Language;
 import net.sourceforge.pmd.lang.LanguageRegistry;
 import net.sourceforge.pmd.lang.LanguageVersion;
@@ -56,7 +53,6 @@ import net.sourceforge.pmd.properties.PropertyDescriptor;
 import net.sourceforge.pmd.properties.PropertySerializer;
 import net.sourceforge.pmd.properties.PropertyTypeId;
 import net.sourceforge.pmd.properties.PropertyTypeId.BuilderAndMapper;
-import net.sourceforge.pmd.rule.Rule;
 import net.sourceforge.pmd.util.ResourceLoader;
 import net.sourceforge.pmd.util.StringUtil;
 import net.sourceforge.pmd.util.internal.xml.PmdXmlReporter;
@@ -75,9 +71,7 @@ import com.github.oowekyala.ooxml.messages.XmlException;
  * @author Clément Fournier
  * @since 6.0.0
  */
-@InternalApi
-@Deprecated
-public class RuleFactory {
+class RuleFactory {
 
     private final ResourceLoader resourceLoader;
     private final LanguageRegistry languageRegistry;
@@ -85,7 +79,7 @@ public class RuleFactory {
     /**
      * @param resourceLoader The resource loader to load the rule from jar
      */
-    public RuleFactory(ResourceLoader resourceLoader,
+    RuleFactory(ResourceLoader resourceLoader,
                        LanguageRegistry languageRegistry) {
         this.resourceLoader = resourceLoader;
         this.languageRegistry = languageRegistry;
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/RulePriority.java b/pmd-core/src/main/java/net/sourceforge/pmd/rule/RulePriority.java
similarity index 99%
rename from pmd-core/src/main/java/net/sourceforge/pmd/RulePriority.java
rename to pmd-core/src/main/java/net/sourceforge/pmd/rule/RulePriority.java
index 8f8b97996b..08cde9f3ee 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/RulePriority.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/rule/RulePriority.java
@@ -2,7 +2,7 @@
  * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
  */
 
-package net.sourceforge.pmd;
+package net.sourceforge.pmd.rule;
 
 /**
  * These are the possible Rule priority values.
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/RuleSet.java b/pmd-core/src/main/java/net/sourceforge/pmd/rule/RuleSet.java
similarity index 99%
rename from pmd-core/src/main/java/net/sourceforge/pmd/RuleSet.java
rename to pmd-core/src/main/java/net/sourceforge/pmd/rule/RuleSet.java
index 3f5f149e7b..9c44c29d7e 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/RuleSet.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/rule/RuleSet.java
@@ -2,7 +2,7 @@
  * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
  */
 
-package net.sourceforge.pmd;
+package net.sourceforge.pmd.rule;
 
 import java.util.ArrayList;
 import java.util.Arrays;
@@ -28,7 +28,6 @@ import net.sourceforge.pmd.lang.document.FileId;
 import net.sourceforge.pmd.lang.document.TextFile;
 import net.sourceforge.pmd.lang.rule.RuleReference;
 import net.sourceforge.pmd.lang.rule.XPathRule;
-import net.sourceforge.pmd.rule.Rule;
 
 /**
  * This class represents a collection of rules along with some optional filter
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/RuleSetFactory.java b/pmd-core/src/main/java/net/sourceforge/pmd/rule/RuleSetFactory.java
similarity index 99%
rename from pmd-core/src/main/java/net/sourceforge/pmd/RuleSetFactory.java
rename to pmd-core/src/main/java/net/sourceforge/pmd/rule/RuleSetFactory.java
index 81e7b1675a..20a2e1ab7e 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/RuleSetFactory.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/rule/RuleSetFactory.java
@@ -2,7 +2,7 @@
  * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
  */
 
-package net.sourceforge.pmd;
+package net.sourceforge.pmd.rule;
 
 import static net.sourceforge.pmd.util.CollectionUtil.setOf;
 import static net.sourceforge.pmd.util.internal.xml.SchemaConstants.DESCRIPTION;
@@ -45,11 +45,10 @@ import org.w3c.dom.Node;
 import org.w3c.dom.NodeList;
 import org.xml.sax.InputSource;
 
-import net.sourceforge.pmd.RuleSet.RuleSetBuilder;
+import net.sourceforge.pmd.PMDVersion;
 import net.sourceforge.pmd.lang.LanguageRegistry;
 import net.sourceforge.pmd.lang.rule.RuleReference;
-import net.sourceforge.pmd.rule.Rule;
-import net.sourceforge.pmd.rules.RuleFactory;
+import net.sourceforge.pmd.rule.RuleSet.RuleSetBuilder;
 import net.sourceforge.pmd.util.ResourceLoader;
 import net.sourceforge.pmd.util.StringUtil;
 import net.sourceforge.pmd.util.internal.xml.PmdXmlReporter;
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/RuleSetFactoryCompatibility.java b/pmd-core/src/main/java/net/sourceforge/pmd/rule/RuleSetFactoryCompatibility.java
similarity index 99%
rename from pmd-core/src/main/java/net/sourceforge/pmd/RuleSetFactoryCompatibility.java
rename to pmd-core/src/main/java/net/sourceforge/pmd/rule/RuleSetFactoryCompatibility.java
index 610676a92c..11f2c9c37f 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/RuleSetFactoryCompatibility.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/rule/RuleSetFactoryCompatibility.java
@@ -2,7 +2,7 @@
  * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
  */
 
-package net.sourceforge.pmd;
+package net.sourceforge.pmd.rule;
 
 import java.text.MessageFormat;
 import java.util.ArrayList;
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/RuleSetLoadException.java b/pmd-core/src/main/java/net/sourceforge/pmd/rule/RuleSetLoadException.java
similarity index 96%
rename from pmd-core/src/main/java/net/sourceforge/pmd/RuleSetLoadException.java
rename to pmd-core/src/main/java/net/sourceforge/pmd/rule/RuleSetLoadException.java
index b83355e1c6..dd4156cceb 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/RuleSetLoadException.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/rule/RuleSetLoadException.java
@@ -2,7 +2,7 @@
  * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
  */
 
-package net.sourceforge.pmd;
+package net.sourceforge.pmd.rule;
 
 import org.checkerframework.checker.nullness.qual.NonNull;
 
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/RuleSetLoader.java b/pmd-core/src/main/java/net/sourceforge/pmd/rule/RuleSetLoader.java
similarity index 99%
rename from pmd-core/src/main/java/net/sourceforge/pmd/RuleSetLoader.java
rename to pmd-core/src/main/java/net/sourceforge/pmd/rule/RuleSetLoader.java
index 08032a14b6..9f238348a1 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/RuleSetLoader.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/rule/RuleSetLoader.java
@@ -2,7 +2,7 @@
  * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
  */
 
-package net.sourceforge.pmd;
+package net.sourceforge.pmd.rule;
 
 import java.io.ByteArrayInputStream;
 import java.io.IOException;
@@ -21,10 +21,10 @@ import org.checkerframework.checker.nullness.qual.Nullable;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import net.sourceforge.pmd.PMDConfiguration;
 import net.sourceforge.pmd.annotation.InternalApi;
 import net.sourceforge.pmd.lang.Language;
 import net.sourceforge.pmd.lang.LanguageRegistry;
-import net.sourceforge.pmd.rule.Rule;
 import net.sourceforge.pmd.util.CollectionUtil;
 import net.sourceforge.pmd.util.ResourceLoader;
 import net.sourceforge.pmd.util.log.MessageReporter;
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/RuleSetReference.java b/pmd-core/src/main/java/net/sourceforge/pmd/rule/RuleSetReference.java
similarity index 97%
rename from pmd-core/src/main/java/net/sourceforge/pmd/RuleSetReference.java
rename to pmd-core/src/main/java/net/sourceforge/pmd/rule/RuleSetReference.java
index cdc6e5f77c..5e6d7cd3cd 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/RuleSetReference.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/rule/RuleSetReference.java
@@ -2,7 +2,7 @@
  * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
  */
 
-package net.sourceforge.pmd;
+package net.sourceforge.pmd.rule;
 
 import java.util.Collections;
 import java.util.LinkedHashSet;
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/RuleSetReferenceId.java b/pmd-core/src/main/java/net/sourceforge/pmd/rule/RuleSetReferenceId.java
similarity index 98%
rename from pmd-core/src/main/java/net/sourceforge/pmd/RuleSetReferenceId.java
rename to pmd-core/src/main/java/net/sourceforge/pmd/rule/RuleSetReferenceId.java
index 7afa4f78b2..c21f7f7254 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/RuleSetReferenceId.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/rule/RuleSetReferenceId.java
@@ -2,7 +2,7 @@
  * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
  */
 
-package net.sourceforge.pmd;
+package net.sourceforge.pmd.rule;
 
 import java.io.File;
 import java.io.FileNotFoundException;
@@ -17,7 +17,6 @@ import java.util.Objects;
 import org.apache.commons.lang3.StringUtils;
 import org.checkerframework.checker.nullness.qual.Nullable;
 
-import net.sourceforge.pmd.annotation.InternalApi;
 import net.sourceforge.pmd.util.ResourceLoader;
 import net.sourceforge.pmd.util.log.MessageReporter;
 
@@ -74,11 +73,9 @@ import net.sourceforge.pmd.util.log.MessageReporter;
  * </tbody>
  * </table>
  *
- * @deprecated This is part of the internals of the {@link RuleSetLoader}.
+ * <p>Note: This is part of the internals of the {@link RuleSetLoader}.
  */
-@Deprecated
-@InternalApi
-public class RuleSetReferenceId {
+class RuleSetReferenceId {
 
     // todo this class has issues... What is even an "external" ruleset?
     //  terminology and API should be clarified.
@@ -99,8 +96,7 @@ public class RuleSetReferenceId {
      * @throws IllegalArgumentException
      *             If the ID contains a comma character.
      */
-    public RuleSetReferenceId(final String id) {
-
+    RuleSetReferenceId(final String id) {
         this(id, null, null);
     }
 
@@ -127,7 +123,7 @@ public class RuleSetReferenceId {
      * @throws IllegalArgumentException If the ID is not Rule reference when there is an external
      *                                  RuleSetReferenceId.
      */
-    public RuleSetReferenceId(final String id, final RuleSetReferenceId externalRuleSetReferenceId) {
+    RuleSetReferenceId(final String id, final RuleSetReferenceId externalRuleSetReferenceId) {
         this(id, externalRuleSetReferenceId, null);
     }
 
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/RuleSetWriter.java b/pmd-core/src/main/java/net/sourceforge/pmd/rule/RuleSetWriter.java
similarity index 99%
rename from pmd-core/src/main/java/net/sourceforge/pmd/RuleSetWriter.java
rename to pmd-core/src/main/java/net/sourceforge/pmd/rule/RuleSetWriter.java
index 88e3757635..55b24ba0ad 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/RuleSetWriter.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/rule/RuleSetWriter.java
@@ -2,7 +2,7 @@
  * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
  */
 
-package net.sourceforge.pmd;
+package net.sourceforge.pmd.rule;
 
 import java.io.OutputStream;
 import java.util.HashSet;
@@ -40,7 +40,6 @@ import net.sourceforge.pmd.properties.PropertyDescriptor;
 import net.sourceforge.pmd.properties.PropertySerializer;
 import net.sourceforge.pmd.properties.PropertySource;
 import net.sourceforge.pmd.properties.PropertyTypeId;
-import net.sourceforge.pmd.rule.Rule;
 import net.sourceforge.pmd.util.internal.xml.SchemaConstants;
 
 /**
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/RuleSets.java b/pmd-core/src/main/java/net/sourceforge/pmd/rule/RuleSets.java
similarity index 99%
rename from pmd-core/src/main/java/net/sourceforge/pmd/RuleSets.java
rename to pmd-core/src/main/java/net/sourceforge/pmd/rule/RuleSets.java
index 062c527635..74d696e327 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/RuleSets.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/rule/RuleSets.java
@@ -2,7 +2,7 @@
  * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
  */
 
-package net.sourceforge.pmd;
+package net.sourceforge.pmd.rule;
 
 import java.util.ArrayList;
 import java.util.Collection;
@@ -21,7 +21,6 @@ import net.sourceforge.pmd.lang.ast.RootNode;
 import net.sourceforge.pmd.lang.document.TextFile;
 import net.sourceforge.pmd.lang.rule.internal.RuleApplicator;
 import net.sourceforge.pmd.reporting.FileAnalysisListener;
-import net.sourceforge.pmd.rule.Rule;
 import net.sourceforge.pmd.util.log.MessageReporter;
 
 /**
diff --git a/pmd-core/src/test/java/net/sourceforge/pmd/AbstractRuleTest.java b/pmd-core/src/test/java/net/sourceforge/pmd/AbstractRuleTest.java
index bc82f3452c..aa90355377 100644
--- a/pmd-core/src/test/java/net/sourceforge/pmd/AbstractRuleTest.java
+++ b/pmd-core/src/test/java/net/sourceforge/pmd/AbstractRuleTest.java
@@ -29,6 +29,7 @@ import net.sourceforge.pmd.lang.rule.ParametricRuleViolation;
 import net.sourceforge.pmd.properties.PropertyDescriptor;
 import net.sourceforge.pmd.properties.PropertyFactory;
 import net.sourceforge.pmd.reporting.FileAnalysisListener;
+import net.sourceforge.pmd.rule.RulePriority;
 
 
 class AbstractRuleTest {
diff --git a/pmd-core/src/test/java/net/sourceforge/pmd/PmdAnalysisTest.java b/pmd-core/src/test/java/net/sourceforge/pmd/PmdAnalysisTest.java
index 8095c7a009..4dabeccf99 100644
--- a/pmd-core/src/test/java/net/sourceforge/pmd/PmdAnalysisTest.java
+++ b/pmd-core/src/test/java/net/sourceforge/pmd/PmdAnalysisTest.java
@@ -22,7 +22,6 @@ import org.junit.jupiter.api.Test;
 import org.mockito.ArgumentMatchers;
 import org.mockito.Mockito;
 
-import net.sourceforge.pmd.RuleSetTest.MockRule;
 import net.sourceforge.pmd.lang.Dummy2LanguageModule;
 import net.sourceforge.pmd.lang.DummyLanguageModule;
 import net.sourceforge.pmd.lang.Language;
@@ -33,6 +32,8 @@ import net.sourceforge.pmd.lang.document.SimpleTestTextFile;
 import net.sourceforge.pmd.lang.rule.AbstractRule;
 import net.sourceforge.pmd.renderers.Renderer;
 import net.sourceforge.pmd.reporting.ReportStats;
+import net.sourceforge.pmd.rule.MockRule;
+import net.sourceforge.pmd.rule.RuleSet;
 import net.sourceforge.pmd.util.log.MessageReporter;
 
 /**
diff --git a/pmd-core/src/test/java/net/sourceforge/pmd/PmdConfigurationTest.java b/pmd-core/src/test/java/net/sourceforge/pmd/PmdConfigurationTest.java
index 036a03ee85..8ab1020315 100644
--- a/pmd-core/src/test/java/net/sourceforge/pmd/PmdConfigurationTest.java
+++ b/pmd-core/src/test/java/net/sourceforge/pmd/PmdConfigurationTest.java
@@ -35,6 +35,7 @@ import net.sourceforge.pmd.cache.NoopAnalysisCache;
 import net.sourceforge.pmd.internal.util.ClasspathClassLoader;
 import net.sourceforge.pmd.renderers.CSVRenderer;
 import net.sourceforge.pmd.renderers.Renderer;
+import net.sourceforge.pmd.rule.RulePriority;
 
 class PmdConfigurationTest {
 
diff --git a/pmd-core/src/test/java/net/sourceforge/pmd/ReportTestUtil.java b/pmd-core/src/test/java/net/sourceforge/pmd/ReportTestUtil.java
index fd455f4811..91c56afacb 100644
--- a/pmd-core/src/test/java/net/sourceforge/pmd/ReportTestUtil.java
+++ b/pmd-core/src/test/java/net/sourceforge/pmd/ReportTestUtil.java
@@ -11,6 +11,8 @@ import net.sourceforge.pmd.lang.ast.Node;
 import net.sourceforge.pmd.lang.ast.RootNode;
 import net.sourceforge.pmd.lang.document.TestMessageReporter;
 import net.sourceforge.pmd.rule.Rule;
+import net.sourceforge.pmd.rule.RuleSet;
+import net.sourceforge.pmd.rule.RuleSets;
 
 public final class ReportTestUtil {
     private ReportTestUtil() {
diff --git a/pmd-core/src/test/java/net/sourceforge/pmd/cache/FileAnalysisCacheTest.java b/pmd-core/src/test/java/net/sourceforge/pmd/cache/FileAnalysisCacheTest.java
index 069f51f48b..b1cf43bf29 100644
--- a/pmd-core/src/test/java/net/sourceforge/pmd/cache/FileAnalysisCacheTest.java
+++ b/pmd-core/src/test/java/net/sourceforge/pmd/cache/FileAnalysisCacheTest.java
@@ -36,7 +36,6 @@ import org.junit.jupiter.api.io.TempDir;
 import org.mockito.Mockito;
 
 import net.sourceforge.pmd.PmdCoreTestUtils;
-import net.sourceforge.pmd.RuleSets;
 import net.sourceforge.pmd.RuleViolation;
 import net.sourceforge.pmd.lang.Language;
 import net.sourceforge.pmd.lang.LanguageVersion;
@@ -49,6 +48,7 @@ import net.sourceforge.pmd.lang.document.TextRange2d;
 import net.sourceforge.pmd.lang.rule.ParametricRuleViolation;
 import net.sourceforge.pmd.reporting.FileAnalysisListener;
 import net.sourceforge.pmd.rule.Rule;
+import net.sourceforge.pmd.rule.RuleSets;
 
 class FileAnalysisCacheTest {
 
diff --git a/pmd-core/src/test/java/net/sourceforge/pmd/lang/impl/AbstractPMDProcessorTest.java b/pmd-core/src/test/java/net/sourceforge/pmd/lang/impl/AbstractPMDProcessorTest.java
index ca52a03e65..a4be8f6a8a 100644
--- a/pmd-core/src/test/java/net/sourceforge/pmd/lang/impl/AbstractPMDProcessorTest.java
+++ b/pmd-core/src/test/java/net/sourceforge/pmd/lang/impl/AbstractPMDProcessorTest.java
@@ -17,7 +17,6 @@ import net.sourceforge.pmd.PMDConfiguration;
 import net.sourceforge.pmd.PmdAnalysis;
 import net.sourceforge.pmd.Report;
 import net.sourceforge.pmd.RuleContext;
-import net.sourceforge.pmd.RuleSet;
 import net.sourceforge.pmd.RuleViolation;
 import net.sourceforge.pmd.lang.DummyLanguageModule;
 import net.sourceforge.pmd.lang.LanguageProcessor;
@@ -28,6 +27,7 @@ import net.sourceforge.pmd.lang.document.TextFile;
 import net.sourceforge.pmd.lang.rule.AbstractRule;
 import net.sourceforge.pmd.reporting.FileAnalysisListener;
 import net.sourceforge.pmd.reporting.GlobalAnalysisListener;
+import net.sourceforge.pmd.rule.RuleSet;
 import net.sourceforge.pmd.util.log.MessageReporter;
 
 abstract class AbstractPMDProcessorTest {
diff --git a/pmd-core/src/test/java/net/sourceforge/pmd/lang/impl/MonoThreadProcessorTest.java b/pmd-core/src/test/java/net/sourceforge/pmd/lang/impl/MonoThreadProcessorTest.java
index 755003142b..073ee36199 100644
--- a/pmd-core/src/test/java/net/sourceforge/pmd/lang/impl/MonoThreadProcessorTest.java
+++ b/pmd-core/src/test/java/net/sourceforge/pmd/lang/impl/MonoThreadProcessorTest.java
@@ -11,7 +11,7 @@ import org.junit.jupiter.api.Test;
 import org.mockito.Mockito;
 
 import net.sourceforge.pmd.PmdAnalysis;
-import net.sourceforge.pmd.RuleSet;
+import net.sourceforge.pmd.rule.RuleSet;
 
 class MonoThreadProcessorTest extends AbstractPMDProcessorTest {
 
diff --git a/pmd-core/src/test/java/net/sourceforge/pmd/lang/impl/MultiThreadProcessorTest.java b/pmd-core/src/test/java/net/sourceforge/pmd/lang/impl/MultiThreadProcessorTest.java
index 12e381fac1..8feda5a284 100644
--- a/pmd-core/src/test/java/net/sourceforge/pmd/lang/impl/MultiThreadProcessorTest.java
+++ b/pmd-core/src/test/java/net/sourceforge/pmd/lang/impl/MultiThreadProcessorTest.java
@@ -15,9 +15,9 @@ import org.mockito.Mockito;
 
 import net.sourceforge.pmd.PmdAnalysis;
 import net.sourceforge.pmd.RuleContext;
-import net.sourceforge.pmd.RuleSet;
 import net.sourceforge.pmd.lang.ast.Node;
 import net.sourceforge.pmd.lang.rule.AbstractRule;
+import net.sourceforge.pmd.rule.RuleSet;
 
 class MultiThreadProcessorTest extends AbstractPMDProcessorTest {
 
diff --git a/pmd-core/src/test/java/net/sourceforge/pmd/lang/rule/MockRule.java b/pmd-core/src/test/java/net/sourceforge/pmd/lang/rule/MockRule.java
index e3b760674d..bea03e58ff 100644
--- a/pmd-core/src/test/java/net/sourceforge/pmd/lang/rule/MockRule.java
+++ b/pmd-core/src/test/java/net/sourceforge/pmd/lang/rule/MockRule.java
@@ -7,10 +7,10 @@ package net.sourceforge.pmd.lang.rule;
 import static net.sourceforge.pmd.properties.NumericConstraints.inRange;
 
 import net.sourceforge.pmd.RuleContext;
-import net.sourceforge.pmd.RulePriority;
 import net.sourceforge.pmd.lang.ast.Node;
 import net.sourceforge.pmd.properties.PropertyDescriptor;
 import net.sourceforge.pmd.properties.PropertyFactory;
+import net.sourceforge.pmd.rule.RulePriority;
 
 
 /**
diff --git a/pmd-core/src/test/java/net/sourceforge/pmd/lang/rule/MockRuleWithNoProperties.java b/pmd-core/src/test/java/net/sourceforge/pmd/lang/rule/MockRuleWithNoProperties.java
index ec4f081756..891657072a 100644
--- a/pmd-core/src/test/java/net/sourceforge/pmd/lang/rule/MockRuleWithNoProperties.java
+++ b/pmd-core/src/test/java/net/sourceforge/pmd/lang/rule/MockRuleWithNoProperties.java
@@ -5,8 +5,8 @@
 package net.sourceforge.pmd.lang.rule;
 
 import net.sourceforge.pmd.RuleContext;
-import net.sourceforge.pmd.RulePriority;
 import net.sourceforge.pmd.lang.ast.Node;
+import net.sourceforge.pmd.rule.RulePriority;
 
 
 /**
diff --git a/pmd-core/src/test/java/net/sourceforge/pmd/processor/PmdRunnableTest.java b/pmd-core/src/test/java/net/sourceforge/pmd/processor/PmdRunnableTest.java
index 71e4388659..dbfde85c78 100644
--- a/pmd-core/src/test/java/net/sourceforge/pmd/processor/PmdRunnableTest.java
+++ b/pmd-core/src/test/java/net/sourceforge/pmd/processor/PmdRunnableTest.java
@@ -29,7 +29,6 @@ import net.sourceforge.pmd.PmdAnalysis;
 import net.sourceforge.pmd.Report;
 import net.sourceforge.pmd.Report.ProcessingError;
 import net.sourceforge.pmd.RuleContext;
-import net.sourceforge.pmd.RuleSet;
 import net.sourceforge.pmd.internal.SystemProps;
 import net.sourceforge.pmd.lang.DummyLanguageModule;
 import net.sourceforge.pmd.lang.LanguageRegistry;
@@ -41,6 +40,7 @@ import net.sourceforge.pmd.lang.document.FileId;
 import net.sourceforge.pmd.lang.impl.SimpleLanguageModuleBase;
 import net.sourceforge.pmd.lang.rule.AbstractRule;
 import net.sourceforge.pmd.rule.Rule;
+import net.sourceforge.pmd.rule.RuleSet;
 import net.sourceforge.pmd.util.ContextedAssertionError;
 import net.sourceforge.pmd.util.log.MessageReporter;
 
diff --git a/pmd-core/src/test/java/net/sourceforge/pmd/properties/PropertySyntaxTest.java b/pmd-core/src/test/java/net/sourceforge/pmd/properties/PropertySyntaxTest.java
index a6e7582f5d..204a1b6bd8 100644
--- a/pmd-core/src/test/java/net/sourceforge/pmd/properties/PropertySyntaxTest.java
+++ b/pmd-core/src/test/java/net/sourceforge/pmd/properties/PropertySyntaxTest.java
@@ -13,8 +13,8 @@ import java.util.ArrayList;
 
 import org.junit.jupiter.api.Test;
 
-import net.sourceforge.pmd.RulesetFactoryTestBase;
 import net.sourceforge.pmd.rule.Rule;
+import net.sourceforge.pmd.rule.RulesetFactoryTestBase;
 import net.sourceforge.pmd.util.internal.xml.XmlErrorMessages;
 
 /**
diff --git a/pmd-core/src/test/java/net/sourceforge/pmd/renderers/AbstractRendererTest.java b/pmd-core/src/test/java/net/sourceforge/pmd/renderers/AbstractRendererTest.java
index 6f16fa705e..cb98fafa56 100644
--- a/pmd-core/src/test/java/net/sourceforge/pmd/renderers/AbstractRendererTest.java
+++ b/pmd-core/src/test/java/net/sourceforge/pmd/renderers/AbstractRendererTest.java
@@ -25,7 +25,6 @@ import net.sourceforge.pmd.FooRule;
 import net.sourceforge.pmd.Report;
 import net.sourceforge.pmd.Report.ConfigurationError;
 import net.sourceforge.pmd.Report.ProcessingError;
-import net.sourceforge.pmd.RulePriority;
 import net.sourceforge.pmd.RuleViolation;
 import net.sourceforge.pmd.RuleWithProperties;
 import net.sourceforge.pmd.internal.util.IOUtil;
@@ -39,6 +38,7 @@ import net.sourceforge.pmd.lang.rule.ParametricRuleViolation;
 import net.sourceforge.pmd.reporting.FileAnalysisListener;
 import net.sourceforge.pmd.reporting.GlobalAnalysisListener;
 import net.sourceforge.pmd.rule.Rule;
+import net.sourceforge.pmd.rule.RulePriority;
 
 abstract class AbstractRendererTest {
 
diff --git a/pmd-core/src/test/java/net/sourceforge/pmd/reporting/GlobalAnalysisListenerTest.java b/pmd-core/src/test/java/net/sourceforge/pmd/reporting/GlobalAnalysisListenerTest.java
index 70a776bf49..3da7d7b0da 100644
--- a/pmd-core/src/test/java/net/sourceforge/pmd/reporting/GlobalAnalysisListenerTest.java
+++ b/pmd-core/src/test/java/net/sourceforge/pmd/reporting/GlobalAnalysisListenerTest.java
@@ -22,13 +22,13 @@ import net.sourceforge.pmd.FooRule;
 import net.sourceforge.pmd.PMDConfiguration;
 import net.sourceforge.pmd.PmdAnalysis;
 import net.sourceforge.pmd.RuleContext;
-import net.sourceforge.pmd.RuleSet;
 import net.sourceforge.pmd.cache.AnalysisCache;
 import net.sourceforge.pmd.cache.NoopAnalysisCache;
 import net.sourceforge.pmd.lang.ast.FileAnalysisException;
 import net.sourceforge.pmd.lang.ast.Node;
 import net.sourceforge.pmd.lang.document.FileId;
 import net.sourceforge.pmd.rule.Rule;
+import net.sourceforge.pmd.rule.RuleSet;
 
 class GlobalAnalysisListenerTest {
 
diff --git a/pmd-core/src/test/java/net/sourceforge/pmd/rule/MockRule.java b/pmd-core/src/test/java/net/sourceforge/pmd/rule/MockRule.java
new file mode 100644
index 0000000000..93395bc1dc
--- /dev/null
+++ b/pmd-core/src/test/java/net/sourceforge/pmd/rule/MockRule.java
@@ -0,0 +1,24 @@
+/*
+ * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
+ */
+
+package net.sourceforge.pmd.rule;
+
+import net.sourceforge.pmd.lang.DummyLanguageModule;
+
+public class MockRule extends net.sourceforge.pmd.lang.rule.MockRule {
+    public MockRule() {
+        super();
+        setLanguage(DummyLanguageModule.getInstance());
+    }
+
+    public MockRule(String name, String description, String message, String ruleSetName, RulePriority priority) {
+        super(name, description, message, ruleSetName, priority);
+        setLanguage(DummyLanguageModule.getInstance());
+    }
+
+    public MockRule(String name, String description, String message, String ruleSetName) {
+        super(name, description, message, ruleSetName);
+        setLanguage(DummyLanguageModule.getInstance());
+    }
+}
diff --git a/pmd-core/src/test/java/net/sourceforge/pmd/RuleReferenceTest.java b/pmd-core/src/test/java/net/sourceforge/pmd/rule/RuleReferenceTest.java
similarity index 99%
rename from pmd-core/src/test/java/net/sourceforge/pmd/RuleReferenceTest.java
rename to pmd-core/src/test/java/net/sourceforge/pmd/rule/RuleReferenceTest.java
index 038481b979..17f4eacfe3 100644
--- a/pmd-core/src/test/java/net/sourceforge/pmd/RuleReferenceTest.java
+++ b/pmd-core/src/test/java/net/sourceforge/pmd/rule/RuleReferenceTest.java
@@ -2,7 +2,7 @@
  * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
  */
 
-package net.sourceforge.pmd;
+package net.sourceforge.pmd.rule;
 
 import static net.sourceforge.pmd.PmdCoreTestUtils.dummyLanguage;
 import static org.junit.jupiter.api.Assertions.assertEquals;
diff --git a/pmd-core/src/test/java/net/sourceforge/pmd/RuleSetFactoryCompatibilityTest.java b/pmd-core/src/test/java/net/sourceforge/pmd/rule/RuleSetFactoryCompatibilityTest.java
similarity index 99%
rename from pmd-core/src/test/java/net/sourceforge/pmd/RuleSetFactoryCompatibilityTest.java
rename to pmd-core/src/test/java/net/sourceforge/pmd/rule/RuleSetFactoryCompatibilityTest.java
index f9e3c089bb..6f46cad48b 100644
--- a/pmd-core/src/test/java/net/sourceforge/pmd/RuleSetFactoryCompatibilityTest.java
+++ b/pmd-core/src/test/java/net/sourceforge/pmd/rule/RuleSetFactoryCompatibilityTest.java
@@ -2,7 +2,7 @@
  * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
  */
 
-package net.sourceforge.pmd;
+package net.sourceforge.pmd.rule;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
diff --git a/pmd-core/src/test/java/net/sourceforge/pmd/RuleSetFactoryDuplicatedRuleLoggingTest.java b/pmd-core/src/test/java/net/sourceforge/pmd/rule/RuleSetFactoryDuplicatedRuleLoggingTest.java
similarity index 98%
rename from pmd-core/src/test/java/net/sourceforge/pmd/RuleSetFactoryDuplicatedRuleLoggingTest.java
rename to pmd-core/src/test/java/net/sourceforge/pmd/rule/RuleSetFactoryDuplicatedRuleLoggingTest.java
index 7b2296242b..e305bfe8c9 100644
--- a/pmd-core/src/test/java/net/sourceforge/pmd/RuleSetFactoryDuplicatedRuleLoggingTest.java
+++ b/pmd-core/src/test/java/net/sourceforge/pmd/rule/RuleSetFactoryDuplicatedRuleLoggingTest.java
@@ -2,7 +2,7 @@
  * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
  */
 
-package net.sourceforge.pmd;
+package net.sourceforge.pmd.rule;
 
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.containsString;
@@ -12,8 +12,6 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import org.junit.jupiter.api.Test;
 
-import net.sourceforge.pmd.rule.Rule;
-
 import com.github.stefanbirkner.systemlambda.SystemLambda;
 
 class RuleSetFactoryDuplicatedRuleLoggingTest extends RulesetFactoryTestBase {
diff --git a/pmd-core/src/test/java/net/sourceforge/pmd/RuleSetFactoryMessagesTest.java b/pmd-core/src/test/java/net/sourceforge/pmd/rule/RuleSetFactoryMessagesTest.java
similarity index 98%
rename from pmd-core/src/test/java/net/sourceforge/pmd/RuleSetFactoryMessagesTest.java
rename to pmd-core/src/test/java/net/sourceforge/pmd/rule/RuleSetFactoryMessagesTest.java
index 5d35ef24aa..1091ced2de 100644
--- a/pmd-core/src/test/java/net/sourceforge/pmd/RuleSetFactoryMessagesTest.java
+++ b/pmd-core/src/test/java/net/sourceforge/pmd/rule/RuleSetFactoryMessagesTest.java
@@ -2,7 +2,7 @@
  * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
  */
 
-package net.sourceforge.pmd;
+package net.sourceforge.pmd.rule;
 
 import static net.sourceforge.pmd.util.CollectionUtil.listOf;
 import static org.hamcrest.MatcherAssert.assertThat;
@@ -12,7 +12,6 @@ import static org.junit.jupiter.api.Assertions.assertEquals;
 import org.junit.jupiter.api.Test;
 
 import net.sourceforge.pmd.lang.rule.MockRule;
-import net.sourceforge.pmd.rule.Rule;
 import net.sourceforge.pmd.util.internal.xml.SchemaConstants;
 import net.sourceforge.pmd.util.internal.xml.XmlErrorMessages;
 
diff --git a/pmd-core/src/test/java/net/sourceforge/pmd/RuleSetFactoryTest.java b/pmd-core/src/test/java/net/sourceforge/pmd/rule/RuleSetFactoryTest.java
similarity index 97%
rename from pmd-core/src/test/java/net/sourceforge/pmd/RuleSetFactoryTest.java
rename to pmd-core/src/test/java/net/sourceforge/pmd/rule/RuleSetFactoryTest.java
index 80070f3b83..63b8580dfa 100644
--- a/pmd-core/src/test/java/net/sourceforge/pmd/RuleSetFactoryTest.java
+++ b/pmd-core/src/test/java/net/sourceforge/pmd/rule/RuleSetFactoryTest.java
@@ -2,7 +2,7 @@
  * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
  */
 
-package net.sourceforge.pmd;
+package net.sourceforge.pmd.rule;
 
 import static net.sourceforge.pmd.PmdCoreTestUtils.dummyLanguage;
 import static net.sourceforge.pmd.util.CollectionUtil.listOf;
@@ -28,36 +28,37 @@ import org.mockito.Mockito;
 import net.sourceforge.pmd.lang.rule.MockRule;
 import net.sourceforge.pmd.lang.rule.RuleReference;
 import net.sourceforge.pmd.properties.PropertyDescriptor;
-import net.sourceforge.pmd.rule.Rule;
 import net.sourceforge.pmd.util.ResourceLoader;
 import net.sourceforge.pmd.util.internal.xml.SchemaConstants;
 
 import com.github.stefanbirkner.systemlambda.SystemLambda;
 
 class RuleSetFactoryTest extends RulesetFactoryTestBase {
+    private static final String TEST_RULESET_1 = "net/sourceforge/pmd/rule/TestRuleset1.xml";
+    private static final String REFERENCE_RULESET = "net/sourceforge/pmd/rule/reference-ruleset.xml";
 
     @Test
     void testRuleSetFileName() {
         RuleSet rs = new RuleSetLoader().loadFromString("dummyRuleset.xml", EMPTY_RULESET);
         assertEquals("dummyRuleset.xml", rs.getFileName());
 
-        rs = new RuleSetLoader().loadFromResource("net/sourceforge/pmd/TestRuleset1.xml");
-        assertEquals(rs.getFileName(), "net/sourceforge/pmd/TestRuleset1.xml", "wrong RuleSet file name");
+        rs = new RuleSetLoader().loadFromResource(TEST_RULESET_1);
+        assertEquals(rs.getFileName(), TEST_RULESET_1, "wrong RuleSet file name");
     }
 
     @Test
     void testRefs() {
-        RuleSet rs = new RuleSetLoader().loadFromResource("net/sourceforge/pmd/TestRuleset1.xml");
+        RuleSet rs = new RuleSetLoader().loadFromResource(TEST_RULESET_1);
         assertNotNull(rs.getRuleByName("TestRuleRef"));
     }
 
     @Test
     void testExtendedReferences() throws Exception {
-        InputStream in = new ResourceLoader().loadClassPathResourceAsStream("net/sourceforge/pmd/rulesets/reference-ruleset.xml");
+        InputStream in = new ResourceLoader().loadClassPathResourceAsStream(REFERENCE_RULESET);
         assertNotNull(in, "Test ruleset not found - can't continue with test!");
         in.close();
 
-        RuleSet rs = new RuleSetLoader().loadFromResource("net/sourceforge/pmd/rulesets/reference-ruleset.xml");
+        RuleSet rs = new RuleSetLoader().loadFromResource(REFERENCE_RULESET);
         // added by referencing a complete ruleset (TestRuleset1.xml)
         assertNotNull(rs.getRuleByName("MockRule1"));
         assertNotNull(rs.getRuleByName("MockRule2"));
@@ -781,7 +782,7 @@ class RuleSetFactoryTest extends RulesetFactoryTestBase {
     void testExternalReferences() {
         RuleSet rs = loadRuleSet(
             rulesetXml(
-                ruleRef("net/sourceforge/pmd/external-reference-ruleset.xml/MockRule")
+                ruleRef("net/sourceforge/pmd/rule/external-reference-ruleset.xml/MockRule")
             )
         );
         assertEquals(1, rs.size());
@@ -858,7 +859,7 @@ class RuleSetFactoryTest extends RulesetFactoryTestBase {
     @Test
     void testWrongRuleNameReferenced() {
         assertCannotParse(rulesetXml(
-            ruleRef("net/sourceforge/pmd/TestRuleset1.xml/ThisRuleDoesNotExist")
+            ruleRef("net/sourceforge/pmd/rule/TestRuleset1.xml/ThisRuleDoesNotExist")
         ));
     }
 
@@ -896,7 +897,7 @@ class RuleSetFactoryTest extends RulesetFactoryTestBase {
                                           + "    xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\"\n"
                                           + "    xsi:schemaLocation=\"http://pmd.sourceforge.net/ruleset/2.0.0 https://pmd.sourceforge.io/ruleset_2_0_0.xsd\">\n"
                                           + "  <description>Custom ruleset for tests</description>\n"
-                                          + "  <rule ref=\"net/sourceforge/pmd/TestRuleset1.xml\">\n"
+                                          + "  <rule ref=\"net/sourceforge/pmd/rule/TestRuleset1.xml\">\n"
                                           + "    <exclude name=\"ThisRuleDoesNotExist\"/>\n" + "  </rule>\n"
                                           + "</ruleset>\n");
         assertEquals(4, ruleset.getRules().size());
@@ -997,7 +998,7 @@ class RuleSetFactoryTest extends RulesetFactoryTestBase {
         + " <description>testdesc</description>\n"
         + " <rule \n"
         + "\n"
-        + "  ref=\"net/sourceforge/pmd/TestRuleset1.xml/MockRule1\" message=\"TestMessageOverride\"> \n"
+        + "  ref=\"net/sourceforge/pmd/rule/TestRuleset1.xml/MockRule1\" message=\"TestMessageOverride\"> \n"
         + "\n"
         + " </rule>\n"
         + "</ruleset>";
@@ -1007,14 +1008,14 @@ class RuleSetFactoryTest extends RulesetFactoryTestBase {
         + "\n"
         + " <description>testdesc</description>\n"
         + " <rule \n"
-        + "  ref=\"net/sourceforge/pmd/TestRuleset1.xml/FooMockRule1\"> \n"
+        + "  ref=\"net/sourceforge/pmd/rule/TestRuleset1.xml/FooMockRule1\"> \n"
         + " </rule>\n"
         + "</ruleset>";
 
     private static final String REF_OVERRIDE_ORIGINAL_NAME_ONE_ELEM = "<?xml version=\"1.0\"?>\n"
         + "<ruleset name=\"test\">\n"
         + " <description>testdesc</description>\n"
-        + " <rule ref=\"net/sourceforge/pmd/TestRuleset1.xml/MockRule1\" message=\"TestMessageOverride\"/> \n"
+        + " <rule ref=\"net/sourceforge/pmd/rule/TestRuleset1.xml/MockRule1\" message=\"TestMessageOverride\"/> \n"
         + "\n"
         + "</ruleset>";
 
@@ -1022,7 +1023,7 @@ class RuleSetFactoryTest extends RulesetFactoryTestBase {
         + "<ruleset name=\"test\">\n"
         + " <description>testdesc</description>\n"
         + " <rule \n"
-        + "  ref=\"net/sourceforge/pmd/TestRuleset1.xml/MockRule4\" \n"
+        + "  ref=\"net/sourceforge/pmd/rule/TestRuleset1.xml/MockRule4\" \n"
         + "  name=\"TestNameOverride\" \n"
         + "\n"
         + "  message=\"Test message override\"> \n"
@@ -1042,7 +1043,7 @@ class RuleSetFactoryTest extends RulesetFactoryTestBase {
         + "\n"
         + " <description>testdesc</description>\n"
         + " <rule \n"
-        + "  ref=\"net/sourceforge/pmd/TestRuleset1.xml/MockRule4\" \n"
+        + "  ref=\"net/sourceforge/pmd/rule/TestRuleset1.xml/MockRule4\" \n"
         + "  name=\"TestNameOverride\" \n"
         + "\n"
         + "  message=\"Test message override\"> \n"
@@ -1088,7 +1089,7 @@ class RuleSetFactoryTest extends RulesetFactoryTestBase {
         + "<rule \n"
         + "\n"
         + "name=\"ExternalRefRuleName\" \n"
-        + "ref=\"net/sourceforge/pmd/TestRuleset1.xml/MockRule1\"/>\n"
+        + "ref=\"net/sourceforge/pmd/rule/TestRuleset1.xml/MockRule1\"/>\n"
         + " <rule ref=\"ExternalRefRuleName\" name=\"ExternalRefRuleNameRef\"/> \n"
         + "</ruleset>";
 
@@ -1098,7 +1099,7 @@ class RuleSetFactoryTest extends RulesetFactoryTestBase {
         + "<rule \n"
         + "\n"
         + "name=\"ExternalRefRuleName\" \n"
-        + "ref=\"net/sourceforge/pmd/TestRuleset2.xml/TestRule\"/>\n"
+        + "ref=\"net/sourceforge/pmd/rule/TestRuleset2.xml/TestRule\"/>\n"
         + " <rule ref=\"ExternalRefRuleName\" name=\"ExternalRefRuleNameRef\"><priority>2</priority></rule> \n"
         + "\n"
         + " <rule ref=\"ExternalRefRuleNameRef\" name=\"ExternalRefRuleNameRefRef\"><priority>1</priority></rule> \n"
@@ -1158,7 +1159,7 @@ class RuleSetFactoryTest extends RulesetFactoryTestBase {
 
     // Note: Update this RuleSet name to a different RuleSet with deprecated
     // Rules when the Rules are finally removed.
-    private static final String DEPRECATED_RULE_RULESET_NAME = "net/sourceforge/pmd/TestRuleset1.xml";
+    private static final String DEPRECATED_RULE_RULESET_NAME = "net/sourceforge/pmd/rule/TestRuleset1.xml";
 
     // Note: Update this Rule name to a different deprecated Rule when the one
     // listed here is finally removed.
diff --git a/pmd-core/src/test/java/net/sourceforge/pmd/RuleSetReferenceIdTest.java b/pmd-core/src/test/java/net/sourceforge/pmd/rule/RuleSetReferenceIdTest.java
similarity index 99%
rename from pmd-core/src/test/java/net/sourceforge/pmd/RuleSetReferenceIdTest.java
rename to pmd-core/src/test/java/net/sourceforge/pmd/rule/RuleSetReferenceIdTest.java
index 4e271dbbba..ac182bb402 100644
--- a/pmd-core/src/test/java/net/sourceforge/pmd/RuleSetReferenceIdTest.java
+++ b/pmd-core/src/test/java/net/sourceforge/pmd/rule/RuleSetReferenceIdTest.java
@@ -2,7 +2,7 @@
  * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
  */
 
-package net.sourceforge.pmd;
+package net.sourceforge.pmd.rule;
 
 import static com.github.tomakehurst.wiremock.client.WireMock.aResponse;
 import static com.github.tomakehurst.wiremock.client.WireMock.findAll;
diff --git a/pmd-core/src/test/java/net/sourceforge/pmd/RuleSetTest.java b/pmd-core/src/test/java/net/sourceforge/pmd/rule/RuleSetTest.java
similarity index 96%
rename from pmd-core/src/test/java/net/sourceforge/pmd/RuleSetTest.java
rename to pmd-core/src/test/java/net/sourceforge/pmd/rule/RuleSetTest.java
index ce0effc4d0..8c29db3399 100644
--- a/pmd-core/src/test/java/net/sourceforge/pmd/RuleSetTest.java
+++ b/pmd-core/src/test/java/net/sourceforge/pmd/rule/RuleSetTest.java
@@ -2,7 +2,7 @@
  * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
  */
 
-package net.sourceforge.pmd;
+package net.sourceforge.pmd.rule;
 
 import static net.sourceforge.pmd.PmdCoreTestUtils.dummyLanguage;
 import static net.sourceforge.pmd.PmdCoreTestUtils.dummyLanguage2;
@@ -40,16 +40,19 @@ import org.checkerframework.checker.nullness.qual.NonNull;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.RegisterExtension;
 
+import net.sourceforge.pmd.DummyParsingHelper;
+import net.sourceforge.pmd.FooRule;
+import net.sourceforge.pmd.Report;
 import net.sourceforge.pmd.Report.ProcessingError;
-import net.sourceforge.pmd.RuleSet.RuleSetBuilder;
-import net.sourceforge.pmd.lang.DummyLanguageModule;
+import net.sourceforge.pmd.RuleContext;
+import net.sourceforge.pmd.RuleViolation;
 import net.sourceforge.pmd.lang.ast.DummyNode.DummyRootNode;
 import net.sourceforge.pmd.lang.ast.Node;
 import net.sourceforge.pmd.lang.ast.RootNode;
 import net.sourceforge.pmd.lang.document.TextFile;
 import net.sourceforge.pmd.lang.rule.RuleReference;
 import net.sourceforge.pmd.lang.rule.RuleTargetSelector;
-import net.sourceforge.pmd.rule.Rule;
+import net.sourceforge.pmd.rule.RuleSet.RuleSetBuilder;
 
 class RuleSetTest {
 
@@ -573,25 +576,4 @@ class RuleSetTest {
 
         assertThat(report.getViolations(), hasSize(1));
     }
-
-
-    static class MockRule extends net.sourceforge.pmd.lang.rule.MockRule {
-
-        MockRule() {
-            super();
-            setLanguage(DummyLanguageModule.getInstance());
-        }
-
-        MockRule(String name, String description, String message, String ruleSetName, RulePriority priority) {
-            super(name, description, message, ruleSetName, priority);
-            setLanguage(DummyLanguageModule.getInstance());
-        }
-
-        MockRule(String name, String description, String message, String ruleSetName) {
-            super(name, description, message, ruleSetName);
-            setLanguage(DummyLanguageModule.getInstance());
-        }
-
-    }
-
 }
diff --git a/pmd-core/src/test/java/net/sourceforge/pmd/RuleSetWriterTest.java b/pmd-core/src/test/java/net/sourceforge/pmd/rule/RuleSetWriterTest.java
similarity index 97%
rename from pmd-core/src/test/java/net/sourceforge/pmd/RuleSetWriterTest.java
rename to pmd-core/src/test/java/net/sourceforge/pmd/rule/RuleSetWriterTest.java
index b762837b10..0772737633 100644
--- a/pmd-core/src/test/java/net/sourceforge/pmd/RuleSetWriterTest.java
+++ b/pmd-core/src/test/java/net/sourceforge/pmd/rule/RuleSetWriterTest.java
@@ -2,7 +2,7 @@
  * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
  */
 
-package net.sourceforge.pmd;
+package net.sourceforge.pmd.rule;
 
 import static net.sourceforge.pmd.util.CollectionUtil.mapOf;
 import static org.hamcrest.MatcherAssert.assertThat;
@@ -18,9 +18,9 @@ import org.junit.jupiter.api.AfterEach;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
-import net.sourceforge.pmd.RuleSet.RuleSetBuilder;
 import net.sourceforge.pmd.lang.rule.RuleReference;
 import net.sourceforge.pmd.lang.rule.XPathRule;
+import net.sourceforge.pmd.rule.RuleSet.RuleSetBuilder;
 import net.sourceforge.pmd.util.internal.xml.SchemaConstants;
 
 /**
@@ -59,7 +59,7 @@ class RuleSetWriterTest extends RulesetFactoryTestBase {
      */
     @Test
     void testWrite() throws Exception {
-        RuleSet braces = new RuleSetLoader().loadFromResource("net/sourceforge/pmd/TestRuleset1.xml");
+        RuleSet braces = new RuleSetLoader().loadFromResource("net/sourceforge/pmd/rule/TestRuleset1.xml");
         RuleSet ruleSet = new RuleSetBuilder(new Random().nextLong())
                 .withName("ruleset")
                 .withDescription("ruleset description")
diff --git a/pmd-core/src/test/java/net/sourceforge/pmd/RulesetFactoryTestBase.java b/pmd-core/src/test/java/net/sourceforge/pmd/rule/RulesetFactoryTestBase.java
similarity index 98%
rename from pmd-core/src/test/java/net/sourceforge/pmd/RulesetFactoryTestBase.java
rename to pmd-core/src/test/java/net/sourceforge/pmd/rule/RulesetFactoryTestBase.java
index 33ad66894c..39c078b1a8 100644
--- a/pmd-core/src/test/java/net/sourceforge/pmd/RulesetFactoryTestBase.java
+++ b/pmd-core/src/test/java/net/sourceforge/pmd/rule/RulesetFactoryTestBase.java
@@ -2,7 +2,7 @@
  * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
  */
 
-package net.sourceforge.pmd;
+package net.sourceforge.pmd.rule;
 
 import static net.sourceforge.pmd.util.CollectionUtil.buildMap;
 import static org.junit.jupiter.api.Assertions.assertThrows;
@@ -27,8 +27,9 @@ import org.mockito.verification.VerificationMode;
 import org.slf4j.LoggerFactory;
 import org.slf4j.event.Level;
 
+import net.sourceforge.pmd.PMDConfiguration;
+import net.sourceforge.pmd.PmdAnalysis;
 import net.sourceforge.pmd.lang.DummyLanguageModule;
-import net.sourceforge.pmd.rule.Rule;
 import net.sourceforge.pmd.util.internal.xml.SchemaConstant;
 import net.sourceforge.pmd.util.internal.xml.SchemaConstants;
 import net.sourceforge.pmd.util.log.MessageReporter;
diff --git a/pmd-core/src/test/resources/net/sourceforge/pmd/TestRuleset1.xml b/pmd-core/src/test/resources/net/sourceforge/pmd/rule/TestRuleset1.xml
similarity index 88%
rename from pmd-core/src/test/resources/net/sourceforge/pmd/TestRuleset1.xml
rename to pmd-core/src/test/resources/net/sourceforge/pmd/rule/TestRuleset1.xml
index 8055258242..feb2f9396d 100644
--- a/pmd-core/src/test/resources/net/sourceforge/pmd/TestRuleset1.xml
+++ b/pmd-core/src/test/resources/net/sourceforge/pmd/rule/TestRuleset1.xml
@@ -3,8 +3,8 @@
     xsi:schemaLocation="http://pmd.sourceforge.net/ruleset/2.0.0 https://pmd.sourceforge.io/ruleset_2_0_0.xsd">
 
     <description>
-  Ruleset used by test net.sourceforge.pmd.RuleSetWriter and RuleSetFactoryTest
-  </description>
+        Ruleset used by test net.sourceforge.pmd.rule.RuleSetWriter and RuleSetFactoryTest
+    </description>
 
     <rule name="MockRule1" language="dummy" since="1.0" message="Test Rule" class="net.sourceforge.pmd.lang.rule.MockRule"
         externalInfoUrl="${pmd.website.baseurl}/rules/test/TestRuleset1.xml#MockRule">
@@ -30,7 +30,7 @@ Just for test
      </example>
     </rule>
 
-    <rule name="MockRule3" deprecated="true" ref="net/sourceforge/pmd/TestRuleset2.xml/TestRule"/>
+    <rule name="MockRule3" deprecated="true" ref="net/sourceforge/pmd/rule/TestRuleset2.xml/TestRule"/>
 
     <rule name="MockRule4" language="dummy" since="1.0" message="Test Rule"
           class="net.sourceforge.pmd.lang.rule.XPathRule"
@@ -51,6 +51,6 @@ Just for test
     </rule>
 
 
-    <rule name="TestRuleRef" ref="net/sourceforge/pmd/TestRuleset2.xml/TestRule"/>
+    <rule name="TestRuleRef" ref="net/sourceforge/pmd/rule/TestRuleset2.xml/TestRule"/>
 
 </ruleset>
diff --git a/pmd-core/src/test/resources/net/sourceforge/pmd/TestRuleset2.xml b/pmd-core/src/test/resources/net/sourceforge/pmd/rule/TestRuleset2.xml
similarity index 100%
rename from pmd-core/src/test/resources/net/sourceforge/pmd/TestRuleset2.xml
rename to pmd-core/src/test/resources/net/sourceforge/pmd/rule/TestRuleset2.xml
diff --git a/pmd-core/src/test/resources/net/sourceforge/pmd/TestRuleset3.xml b/pmd-core/src/test/resources/net/sourceforge/pmd/rule/TestRuleset3.xml
similarity index 100%
rename from pmd-core/src/test/resources/net/sourceforge/pmd/TestRuleset3.xml
rename to pmd-core/src/test/resources/net/sourceforge/pmd/rule/TestRuleset3.xml
diff --git a/pmd-core/src/test/resources/net/sourceforge/pmd/TestRuleset4.xml b/pmd-core/src/test/resources/net/sourceforge/pmd/rule/TestRuleset4.xml
similarity index 100%
rename from pmd-core/src/test/resources/net/sourceforge/pmd/TestRuleset4.xml
rename to pmd-core/src/test/resources/net/sourceforge/pmd/rule/TestRuleset4.xml
diff --git a/pmd-core/src/test/resources/net/sourceforge/pmd/external-reference-ruleset.xml b/pmd-core/src/test/resources/net/sourceforge/pmd/rule/external-reference-ruleset.xml
similarity index 87%
rename from pmd-core/src/test/resources/net/sourceforge/pmd/external-reference-ruleset.xml
rename to pmd-core/src/test/resources/net/sourceforge/pmd/rule/external-reference-ruleset.xml
index 6515a57737..d9a32bbb12 100644
--- a/pmd-core/src/test/resources/net/sourceforge/pmd/external-reference-ruleset.xml
+++ b/pmd-core/src/test/resources/net/sourceforge/pmd/rule/external-reference-ruleset.xml
@@ -3,8 +3,8 @@
     xsi:schemaLocation="http://pmd.sourceforge.net/ruleset/2.0.0 https://pmd.sourceforge.io/ruleset_2_0_0.xsd">
 
     <description>
-  Ruleset used by test net.sourceforge.pmd.RuleSetFactoryTest
-  </description>
+        Ruleset used by test net.sourceforge.pmd.rule.RuleSetFactoryTest
+    </description>
 
     <rule name="MockRule" language="dummy" since="1.0" message="Test Rule" class="net.sourceforge.pmd.lang.rule.MockRule"
         externalInfoUrl="${pmd.website.baseurl}/rules/test/external-reference-ruleset.html#MockRule">
diff --git a/pmd-core/src/test/resources/net/sourceforge/pmd/rulesets/reference-ruleset.xml b/pmd-core/src/test/resources/net/sourceforge/pmd/rule/reference-ruleset.xml
similarity index 65%
rename from pmd-core/src/test/resources/net/sourceforge/pmd/rulesets/reference-ruleset.xml
rename to pmd-core/src/test/resources/net/sourceforge/pmd/rule/reference-ruleset.xml
index aff963c994..962d1a8366 100644
--- a/pmd-core/src/test/resources/net/sourceforge/pmd/rulesets/reference-ruleset.xml
+++ b/pmd-core/src/test/resources/net/sourceforge/pmd/rule/reference-ruleset.xml
@@ -5,45 +5,45 @@
     xsi:schemaLocation="http://pmd.sourceforge.net/ruleset/2.0.0 https://pmd.sourceforge.io/ruleset_2_0_0.xsd">
 
   <description>
-  This ruleset checks my code for bad stuff
+  This ruleset checks my code for bad stuff. Used by net.sourceforge.pmd.rule.RuleSetFactoryTest.
   </description>
 
   <!-- We'll use the entire 'TestRuleset1' ruleset -->
-  <rule ref="net/sourceforge/pmd/TestRuleset1.xml"/>
+  <rule ref="net/sourceforge/pmd/rule/TestRuleset1.xml"/>
 
   <!-- Here's some rules we'll specify one at a time -->
-  <rule ref="net/sourceforge/pmd/TestRuleset2.xml/TestRule"/>
+  <rule ref="net/sourceforge/pmd/rule/TestRuleset2.xml/TestRule"/>
 
   <!-- We want to customize this rule a bit, change the message and raise the priority  -->
   <!-- Note: This rule is deprecated -->
   <rule
-   ref="net/sourceforge/pmd/TestRuleset1.xml/MockRule3"
+   ref="net/sourceforge/pmd/rule/TestRuleset1.xml/MockRule3"
    message="Overridden message">
     <priority>2</priority>
   </rule>
 
   <!-- Customize just the message for MockRule2 -->
-  <rule ref="net/sourceforge/pmd/TestRuleset1.xml/MockRule2" message="Just combine them!"/>
+  <rule ref="net/sourceforge/pmd/rule/TestRuleset1.xml/MockRule2" message="Just combine them!"/>
 
   <!-- Now we'll customize a rule's property value -->
-  <rule ref="net/sourceforge/pmd/TestRuleset1.xml/MockRule1">
+  <rule ref="net/sourceforge/pmd/rule/TestRuleset1.xml/MockRule1">
     <properties>
         <property name="testIntProperty" value="5"/>
     </properties>
   </rule>
 
   <!-- We want everything from TestRuleset3.xml except Ruleset3Rule1 -->
-  <rule ref="net/sourceforge/pmd/TestRuleset3.xml">
+  <rule ref="net/sourceforge/pmd/rule/TestRuleset3.xml">
     <exclude name="Ruleset3Rule1"/>
   </rule>
 
   <!-- override the priority before the group priority - this should be used -->
-  <rule ref="net/sourceforge/pmd/TestRuleset4.xml/Ruleset4Rule1">
+  <rule ref="net/sourceforge/pmd/rule/TestRuleset4.xml/Ruleset4Rule1">
     <priority>5</priority>
   </rule>
 
   <!-- we want to override the priority for all (remaining) rules in TestRuleset4.xml -->
-  <rule ref="net/sourceforge/pmd/TestRuleset4.xml">
+  <rule ref="net/sourceforge/pmd/rule/TestRuleset4.xml">
     <priority>2</priority>
   </rule>
-</ruleset>
\ No newline at end of file
+</ruleset>
diff --git a/pmd-doc/src/main/java/net/sourceforge/pmd/docs/GenerateRuleDocsCmd.java b/pmd-doc/src/main/java/net/sourceforge/pmd/docs/GenerateRuleDocsCmd.java
index ebe55f4abd..3eb570bc1b 100644
--- a/pmd-doc/src/main/java/net/sourceforge/pmd/docs/GenerateRuleDocsCmd.java
+++ b/pmd-doc/src/main/java/net/sourceforge/pmd/docs/GenerateRuleDocsCmd.java
@@ -17,9 +17,9 @@ import java.util.ArrayList;
 import java.util.List;
 import java.util.regex.Pattern;
 
-import net.sourceforge.pmd.RuleSet;
-import net.sourceforge.pmd.RuleSetLoader;
 import net.sourceforge.pmd.internal.util.IOUtil;
+import net.sourceforge.pmd.rule.RuleSet;
+import net.sourceforge.pmd.rule.RuleSetLoader;
 
 public final class GenerateRuleDocsCmd {
 
diff --git a/pmd-doc/src/main/java/net/sourceforge/pmd/docs/RuleDocGenerator.java b/pmd-doc/src/main/java/net/sourceforge/pmd/docs/RuleDocGenerator.java
index 59c5635a0b..80af73520c 100644
--- a/pmd-doc/src/main/java/net/sourceforge/pmd/docs/RuleDocGenerator.java
+++ b/pmd-doc/src/main/java/net/sourceforge/pmd/docs/RuleDocGenerator.java
@@ -32,9 +32,6 @@ import org.apache.commons.text.StringEscapeUtils;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import net.sourceforge.pmd.RuleSet;
-import net.sourceforge.pmd.RuleSetLoadException;
-import net.sourceforge.pmd.RuleSetLoader;
 import net.sourceforge.pmd.internal.util.IOUtil;
 import net.sourceforge.pmd.lang.Language;
 import net.sourceforge.pmd.lang.LanguageRegistry;
@@ -42,6 +39,9 @@ import net.sourceforge.pmd.lang.rule.RuleReference;
 import net.sourceforge.pmd.lang.rule.XPathRule;
 import net.sourceforge.pmd.properties.PropertyDescriptor;
 import net.sourceforge.pmd.rule.Rule;
+import net.sourceforge.pmd.rule.RuleSet;
+import net.sourceforge.pmd.rule.RuleSetLoadException;
+import net.sourceforge.pmd.rule.RuleSetLoader;
 
 public class RuleDocGenerator {
     private static final Logger LOG = LoggerFactory.getLogger(RuleDocGenerator.class);
diff --git a/pmd-doc/src/main/java/net/sourceforge/pmd/docs/RuleSetUtils.java b/pmd-doc/src/main/java/net/sourceforge/pmd/docs/RuleSetUtils.java
index f4b1d326ea..a575efd90a 100644
--- a/pmd-doc/src/main/java/net/sourceforge/pmd/docs/RuleSetUtils.java
+++ b/pmd-doc/src/main/java/net/sourceforge/pmd/docs/RuleSetUtils.java
@@ -10,10 +10,10 @@ import java.util.regex.Pattern;
 import org.apache.commons.lang3.StringUtils;
 import org.apache.commons.lang3.SystemUtils;
 
-import net.sourceforge.pmd.RuleSet;
 import net.sourceforge.pmd.internal.util.IOUtil;
 import net.sourceforge.pmd.lang.rule.RuleReference;
 import net.sourceforge.pmd.rule.Rule;
+import net.sourceforge.pmd.rule.RuleSet;
 
 public final class RuleSetUtils {
 
diff --git a/pmd-doc/src/main/java/net/sourceforge/pmd/docs/SidebarGenerator.java b/pmd-doc/src/main/java/net/sourceforge/pmd/docs/SidebarGenerator.java
index bcec609c44..d514aac017 100644
--- a/pmd-doc/src/main/java/net/sourceforge/pmd/docs/SidebarGenerator.java
+++ b/pmd-doc/src/main/java/net/sourceforge/pmd/docs/SidebarGenerator.java
@@ -25,8 +25,8 @@ import org.yaml.snakeyaml.Yaml;
 import org.yaml.snakeyaml.constructor.SafeConstructor;
 import org.yaml.snakeyaml.representer.Representer;
 
-import net.sourceforge.pmd.RuleSet;
 import net.sourceforge.pmd.lang.Language;
+import net.sourceforge.pmd.rule.RuleSet;
 
 public class SidebarGenerator {
     private static final String SIDEBAR_YML = "docs/_data/sidebars/pmd_sidebar.yml";
diff --git a/pmd-doc/src/test/java/net/sourceforge/pmd/docs/RuleDocGeneratorTest.java b/pmd-doc/src/test/java/net/sourceforge/pmd/docs/RuleDocGeneratorTest.java
index 69665c54b5..726b63120c 100644
--- a/pmd-doc/src/test/java/net/sourceforge/pmd/docs/RuleDocGeneratorTest.java
+++ b/pmd-doc/src/test/java/net/sourceforge/pmd/docs/RuleDocGeneratorTest.java
@@ -19,10 +19,10 @@ import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.io.TempDir;
 
-import net.sourceforge.pmd.RuleSet;
-import net.sourceforge.pmd.RuleSetLoader;
 import net.sourceforge.pmd.docs.MockedFileWriter.FileEntry;
 import net.sourceforge.pmd.internal.util.IOUtil;
+import net.sourceforge.pmd.rule.RuleSet;
+import net.sourceforge.pmd.rule.RuleSetLoader;
 
 class RuleDocGeneratorTest {
 
diff --git a/pmd-doc/src/test/java/net/sourceforge/pmd/docs/RuleSetResolverTest.java b/pmd-doc/src/test/java/net/sourceforge/pmd/docs/RuleSetResolverTest.java
index f5baf81b34..6bfa114a1a 100644
--- a/pmd-doc/src/test/java/net/sourceforge/pmd/docs/RuleSetResolverTest.java
+++ b/pmd-doc/src/test/java/net/sourceforge/pmd/docs/RuleSetResolverTest.java
@@ -14,8 +14,8 @@ import java.util.List;
 
 import org.junit.jupiter.api.Test;
 
-import net.sourceforge.pmd.RuleSetLoader;
 import net.sourceforge.pmd.internal.util.IOUtil;
+import net.sourceforge.pmd.rule.RuleSetLoader;
 
 class RuleSetResolverTest {
 
diff --git a/pmd-doc/src/test/java/net/sourceforge/pmd/docs/SidebarGeneratorTest.java b/pmd-doc/src/test/java/net/sourceforge/pmd/docs/SidebarGeneratorTest.java
index 8fe3a7d5ef..cdbce4d764 100644
--- a/pmd-doc/src/test/java/net/sourceforge/pmd/docs/SidebarGeneratorTest.java
+++ b/pmd-doc/src/test/java/net/sourceforge/pmd/docs/SidebarGeneratorTest.java
@@ -26,10 +26,10 @@ import org.yaml.snakeyaml.Yaml;
 import org.yaml.snakeyaml.constructor.SafeConstructor;
 import org.yaml.snakeyaml.representer.Representer;
 
-import net.sourceforge.pmd.RuleSet;
 import net.sourceforge.pmd.internal.util.IOUtil;
 import net.sourceforge.pmd.lang.Language;
 import net.sourceforge.pmd.lang.LanguageRegistry;
+import net.sourceforge.pmd.rule.RuleSet;
 
 class SidebarGeneratorTest {
     private MockedFileWriter writer = new MockedFileWriter();
diff --git a/pmd-html/src/test/java/net/sourceforge/pmd/lang/html/RuleSetFactoryTest.java b/pmd-html/src/test/java/net/sourceforge/pmd/lang/html/RuleSetFactoryTest.java
index 7205edf858..4e479ff041 100644
--- a/pmd-html/src/test/java/net/sourceforge/pmd/lang/html/RuleSetFactoryTest.java
+++ b/pmd-html/src/test/java/net/sourceforge/pmd/lang/html/RuleSetFactoryTest.java
@@ -4,7 +4,7 @@
 
 package net.sourceforge.pmd.lang.html;
 
-import net.sourceforge.pmd.AbstractRuleSetFactoryTest;
+import net.sourceforge.pmd.rule.AbstractRuleSetFactoryTest;
 
 class RuleSetFactoryTest extends AbstractRuleSetFactoryTest {
     // no additional tests yet
diff --git a/pmd-java/src/test/java/net/sourceforge/pmd/lang/java/PMD5RulesetTest.java b/pmd-java/src/test/java/net/sourceforge/pmd/lang/java/PMD5RulesetTest.java
index 9334683d33..25714b6e53 100644
--- a/pmd-java/src/test/java/net/sourceforge/pmd/lang/java/PMD5RulesetTest.java
+++ b/pmd-java/src/test/java/net/sourceforge/pmd/lang/java/PMD5RulesetTest.java
@@ -9,8 +9,8 @@ import static org.junit.jupiter.api.Assertions.assertNull;
 
 import org.junit.jupiter.api.Test;
 
-import net.sourceforge.pmd.RuleSet;
-import net.sourceforge.pmd.RuleSetLoader;
+import net.sourceforge.pmd.rule.RuleSet;
+import net.sourceforge.pmd.rule.RuleSetLoader;
 
 class PMD5RulesetTest {
 
diff --git a/pmd-java/src/test/java/net/sourceforge/pmd/lang/java/QuickstartRulesetTest.java b/pmd-java/src/test/java/net/sourceforge/pmd/lang/java/QuickstartRulesetTest.java
index 2b7ffdc9fd..eb5b22ef17 100644
--- a/pmd-java/src/test/java/net/sourceforge/pmd/lang/java/QuickstartRulesetTest.java
+++ b/pmd-java/src/test/java/net/sourceforge/pmd/lang/java/QuickstartRulesetTest.java
@@ -9,9 +9,9 @@ import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import org.junit.jupiter.api.Test;
 
-import net.sourceforge.pmd.AbstractRuleSetFactoryTest;
-import net.sourceforge.pmd.RuleSet;
-import net.sourceforge.pmd.RuleSetLoader;
+import net.sourceforge.pmd.rule.AbstractRuleSetFactoryTest;
+import net.sourceforge.pmd.rule.RuleSet;
+import net.sourceforge.pmd.rule.RuleSetLoader;
 
 import com.github.stefanbirkner.systemlambda.SystemLambda;
 
diff --git a/pmd-java/src/test/java/net/sourceforge/pmd/lang/java/RuleSetFactoryTest.java b/pmd-java/src/test/java/net/sourceforge/pmd/lang/java/RuleSetFactoryTest.java
index d6cafa265a..f11518cf1d 100644
--- a/pmd-java/src/test/java/net/sourceforge/pmd/lang/java/RuleSetFactoryTest.java
+++ b/pmd-java/src/test/java/net/sourceforge/pmd/lang/java/RuleSetFactoryTest.java
@@ -4,7 +4,7 @@
 
 package net.sourceforge.pmd.lang.java;
 
-import net.sourceforge.pmd.AbstractRuleSetFactoryTest;
+import net.sourceforge.pmd.rule.AbstractRuleSetFactoryTest;
 
 /**
  * Test java's rulesets
diff --git a/pmd-javascript/src/test/java/net/sourceforge/pmd/lang/ecmascript/RuleSetFactoryTest.java b/pmd-javascript/src/test/java/net/sourceforge/pmd/lang/ecmascript/RuleSetFactoryTest.java
index 551b583deb..46a9adae40 100644
--- a/pmd-javascript/src/test/java/net/sourceforge/pmd/lang/ecmascript/RuleSetFactoryTest.java
+++ b/pmd-javascript/src/test/java/net/sourceforge/pmd/lang/ecmascript/RuleSetFactoryTest.java
@@ -4,7 +4,7 @@
 
 package net.sourceforge.pmd.lang.ecmascript;
 
-import net.sourceforge.pmd.AbstractRuleSetFactoryTest;
+import net.sourceforge.pmd.rule.AbstractRuleSetFactoryTest;
 
 /**
  * Test javascript's rulesets
diff --git a/pmd-jsp/src/test/java/net/sourceforge/pmd/lang/jsp/RuleSetFactoryTest.java b/pmd-jsp/src/test/java/net/sourceforge/pmd/lang/jsp/RuleSetFactoryTest.java
index 80b8ecbf7a..df499f7f42 100644
--- a/pmd-jsp/src/test/java/net/sourceforge/pmd/lang/jsp/RuleSetFactoryTest.java
+++ b/pmd-jsp/src/test/java/net/sourceforge/pmd/lang/jsp/RuleSetFactoryTest.java
@@ -4,7 +4,7 @@
 
 package net.sourceforge.pmd.lang.jsp;
 
-import net.sourceforge.pmd.AbstractRuleSetFactoryTest;
+import net.sourceforge.pmd.rule.AbstractRuleSetFactoryTest;
 
 /**
  * Test jsp's rulesets
diff --git a/pmd-kotlin/src/test/java/net/sourceforge/pmd/lang/kotlin/RuleSetFactoryTest.java b/pmd-kotlin/src/test/java/net/sourceforge/pmd/lang/kotlin/RuleSetFactoryTest.java
index 9655674f8a..3faa6b6ab2 100644
--- a/pmd-kotlin/src/test/java/net/sourceforge/pmd/lang/kotlin/RuleSetFactoryTest.java
+++ b/pmd-kotlin/src/test/java/net/sourceforge/pmd/lang/kotlin/RuleSetFactoryTest.java
@@ -4,7 +4,7 @@
 
 package net.sourceforge.pmd.lang.kotlin;
 
-import net.sourceforge.pmd.AbstractRuleSetFactoryTest;
+import net.sourceforge.pmd.rule.AbstractRuleSetFactoryTest;
 
 class RuleSetFactoryTest extends AbstractRuleSetFactoryTest {
     // no additional tests yet
diff --git a/pmd-lang-test/src/main/kotlin/net/sourceforge/pmd/lang/ast/test/BaseParsingHelper.kt b/pmd-lang-test/src/main/kotlin/net/sourceforge/pmd/lang/ast/test/BaseParsingHelper.kt
index 6636e487a6..4b00719190 100644
--- a/pmd-lang-test/src/main/kotlin/net/sourceforge/pmd/lang/ast/test/BaseParsingHelper.kt
+++ b/pmd-lang-test/src/main/kotlin/net/sourceforge/pmd/lang/ast/test/BaseParsingHelper.kt
@@ -17,6 +17,7 @@ import net.sourceforge.pmd.lang.rule.XPathRule
 import net.sourceforge.pmd.lang.rule.xpath.XPathVersion
 import net.sourceforge.pmd.reporting.GlobalAnalysisListener
 import net.sourceforge.pmd.rule.Rule
+import net.sourceforge.pmd.rule.RuleSet
 import java.io.InputStream
 import java.nio.charset.StandardCharsets
 import java.nio.file.Files
diff --git a/pmd-modelica/src/test/java/net/sourceforge/pmd/lang/modelica/RuleSetFactoryTest.java b/pmd-modelica/src/test/java/net/sourceforge/pmd/lang/modelica/RuleSetFactoryTest.java
index d515ff6597..6932fa08a1 100644
--- a/pmd-modelica/src/test/java/net/sourceforge/pmd/lang/modelica/RuleSetFactoryTest.java
+++ b/pmd-modelica/src/test/java/net/sourceforge/pmd/lang/modelica/RuleSetFactoryTest.java
@@ -4,7 +4,7 @@
 
 package net.sourceforge.pmd.lang.modelica;
 
-import net.sourceforge.pmd.AbstractRuleSetFactoryTest;
+import net.sourceforge.pmd.rule.AbstractRuleSetFactoryTest;
 
 class RuleSetFactoryTest extends AbstractRuleSetFactoryTest {
     // no additional tests yet
diff --git a/pmd-plsql/src/test/java/net/sourceforge/pmd/lang/plsql/RuleSetFactoryTest.java b/pmd-plsql/src/test/java/net/sourceforge/pmd/lang/plsql/RuleSetFactoryTest.java
index 2fa3b962eb..59518c00bd 100644
--- a/pmd-plsql/src/test/java/net/sourceforge/pmd/lang/plsql/RuleSetFactoryTest.java
+++ b/pmd-plsql/src/test/java/net/sourceforge/pmd/lang/plsql/RuleSetFactoryTest.java
@@ -4,7 +4,7 @@
 
 package net.sourceforge.pmd.lang.plsql;
 
-import net.sourceforge.pmd.AbstractRuleSetFactoryTest;
+import net.sourceforge.pmd.rule.AbstractRuleSetFactoryTest;
 
 /**
  * Test plsql's rulesets
diff --git a/pmd-scala-modules/pmd-scala-common/src/test/java/net/sourceforge/pmd/lang/scala/RulesetFactoryTest.java b/pmd-scala-modules/pmd-scala-common/src/test/java/net/sourceforge/pmd/lang/scala/RulesetFactoryTest.java
index ff8a253296..93ac55200c 100644
--- a/pmd-scala-modules/pmd-scala-common/src/test/java/net/sourceforge/pmd/lang/scala/RulesetFactoryTest.java
+++ b/pmd-scala-modules/pmd-scala-common/src/test/java/net/sourceforge/pmd/lang/scala/RulesetFactoryTest.java
@@ -4,7 +4,7 @@
 
 package net.sourceforge.pmd.lang.scala;
 
-import net.sourceforge.pmd.AbstractRuleSetFactoryTest;
+import net.sourceforge.pmd.rule.AbstractRuleSetFactoryTest;
 
 /**
  * Test scala rulesets
diff --git a/pmd-swift/src/test/java/net/sourceforge/pmd/lang/swift/RuleSetFactoryTest.java b/pmd-swift/src/test/java/net/sourceforge/pmd/lang/swift/RuleSetFactoryTest.java
index f800ac2bea..bd9fb82f51 100644
--- a/pmd-swift/src/test/java/net/sourceforge/pmd/lang/swift/RuleSetFactoryTest.java
+++ b/pmd-swift/src/test/java/net/sourceforge/pmd/lang/swift/RuleSetFactoryTest.java
@@ -4,7 +4,7 @@
 
 package net.sourceforge.pmd.lang.swift;
 
-import net.sourceforge.pmd.AbstractRuleSetFactoryTest;
+import net.sourceforge.pmd.rule.AbstractRuleSetFactoryTest;
 
 class RuleSetFactoryTest extends AbstractRuleSetFactoryTest {
     // no additional unit tests
diff --git a/pmd-test/src/main/java/net/sourceforge/pmd/AbstractLanguageVersionTest.java b/pmd-test/src/main/java/net/sourceforge/pmd/AbstractLanguageVersionTest.java
index 54f0b83b6f..c3eed72f00 100644
--- a/pmd-test/src/main/java/net/sourceforge/pmd/AbstractLanguageVersionTest.java
+++ b/pmd-test/src/main/java/net/sourceforge/pmd/AbstractLanguageVersionTest.java
@@ -19,6 +19,8 @@ import net.sourceforge.pmd.ant.SourceLanguage;
 import net.sourceforge.pmd.lang.Language;
 import net.sourceforge.pmd.lang.LanguageRegistry;
 import net.sourceforge.pmd.lang.LanguageVersion;
+import net.sourceforge.pmd.rule.RuleSet;
+import net.sourceforge.pmd.rule.RuleSetLoader;
 
 /**
  * Base test class for {@link LanguageVersion} implementations. <br>
diff --git a/pmd-test/src/main/java/net/sourceforge/pmd/AbstractRuleSetFactoryTest.java b/pmd-test/src/main/java/net/sourceforge/pmd/rule/AbstractRuleSetFactoryTest.java
similarity index 99%
rename from pmd-test/src/main/java/net/sourceforge/pmd/AbstractRuleSetFactoryTest.java
rename to pmd-test/src/main/java/net/sourceforge/pmd/rule/AbstractRuleSetFactoryTest.java
index 6b6e04c25b..067e1cd78a 100644
--- a/pmd-test/src/main/java/net/sourceforge/pmd/AbstractRuleSetFactoryTest.java
+++ b/pmd-test/src/main/java/net/sourceforge/pmd/rule/AbstractRuleSetFactoryTest.java
@@ -2,7 +2,7 @@
  * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
  */
 
-package net.sourceforge.pmd;
+package net.sourceforge.pmd.rule;
 
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.emptyString;
@@ -48,7 +48,6 @@ import net.sourceforge.pmd.lang.LanguageRegistry;
 import net.sourceforge.pmd.lang.rule.RuleReference;
 import net.sourceforge.pmd.lang.rule.XPathRule;
 import net.sourceforge.pmd.properties.PropertyDescriptor;
-import net.sourceforge.pmd.rule.Rule;
 import net.sourceforge.pmd.util.log.internal.MessageReporterBase;
 
 /**
diff --git a/pmd-test/src/main/java/net/sourceforge/pmd/testframework/RuleTst.java b/pmd-test/src/main/java/net/sourceforge/pmd/testframework/RuleTst.java
index 46443793b2..08d48ff1e7 100644
--- a/pmd-test/src/main/java/net/sourceforge/pmd/testframework/RuleTst.java
+++ b/pmd-test/src/main/java/net/sourceforge/pmd/testframework/RuleTst.java
@@ -27,9 +27,6 @@ import org.xml.sax.InputSource;
 import net.sourceforge.pmd.PMDConfiguration;
 import net.sourceforge.pmd.PmdAnalysis;
 import net.sourceforge.pmd.Report;
-import net.sourceforge.pmd.RuleSet;
-import net.sourceforge.pmd.RuleSetLoadException;
-import net.sourceforge.pmd.RuleSetLoader;
 import net.sourceforge.pmd.RuleViolation;
 import net.sourceforge.pmd.lang.LanguageVersion;
 import net.sourceforge.pmd.lang.document.FileId;
@@ -38,6 +35,9 @@ import net.sourceforge.pmd.properties.PropertyDescriptor;
 import net.sourceforge.pmd.renderers.TextRenderer;
 import net.sourceforge.pmd.reporting.GlobalAnalysisListener;
 import net.sourceforge.pmd.rule.Rule;
+import net.sourceforge.pmd.rule.RuleSet;
+import net.sourceforge.pmd.rule.RuleSetLoadException;
+import net.sourceforge.pmd.rule.RuleSetLoader;
 import net.sourceforge.pmd.test.schema.RuleTestCollection;
 import net.sourceforge.pmd.test.schema.RuleTestDescriptor;
 import net.sourceforge.pmd.test.schema.TestSchemaParser;
diff --git a/pmd-visualforce/src/test/java/net/sourceforge/pmd/lang/vf/RuleSetFactoryTest.java b/pmd-visualforce/src/test/java/net/sourceforge/pmd/lang/vf/RuleSetFactoryTest.java
index 3b020f99b1..ff5782044f 100644
--- a/pmd-visualforce/src/test/java/net/sourceforge/pmd/lang/vf/RuleSetFactoryTest.java
+++ b/pmd-visualforce/src/test/java/net/sourceforge/pmd/lang/vf/RuleSetFactoryTest.java
@@ -4,8 +4,8 @@
 
 package net.sourceforge.pmd.lang.vf;
 
-import net.sourceforge.pmd.AbstractRuleSetFactoryTest;
 import net.sourceforge.pmd.lang.apex.ApexLanguageModule;
+import net.sourceforge.pmd.rule.AbstractRuleSetFactoryTest;
 
 class RuleSetFactoryTest extends AbstractRuleSetFactoryTest {
     RuleSetFactoryTest() {
diff --git a/pmd-vm/src/test/java/net/sourceforge/pmd/lang/vm/RuleSetFactoryTest.java b/pmd-vm/src/test/java/net/sourceforge/pmd/lang/vm/RuleSetFactoryTest.java
index 75037cd663..987532babc 100644
--- a/pmd-vm/src/test/java/net/sourceforge/pmd/lang/vm/RuleSetFactoryTest.java
+++ b/pmd-vm/src/test/java/net/sourceforge/pmd/lang/vm/RuleSetFactoryTest.java
@@ -4,7 +4,7 @@
 
 package net.sourceforge.pmd.lang.vm;
 
-import net.sourceforge.pmd.AbstractRuleSetFactoryTest;
+import net.sourceforge.pmd.rule.AbstractRuleSetFactoryTest;
 
 /**
  * Test velocity's rulesets.
diff --git a/pmd-xml/src/test/java/net/sourceforge/pmd/lang/xml/RuleSetFactoryTest.java b/pmd-xml/src/test/java/net/sourceforge/pmd/lang/xml/RuleSetFactoryTest.java
index b2c4b70e68..9b9934c738 100644
--- a/pmd-xml/src/test/java/net/sourceforge/pmd/lang/xml/RuleSetFactoryTest.java
+++ b/pmd-xml/src/test/java/net/sourceforge/pmd/lang/xml/RuleSetFactoryTest.java
@@ -4,7 +4,7 @@
 
 package net.sourceforge.pmd.lang.xml;
 
-import net.sourceforge.pmd.AbstractRuleSetFactoryTest;
+import net.sourceforge.pmd.rule.AbstractRuleSetFactoryTest;
 
 /**
  * Test xml's and xslt's rulesets