diff --git a/docs/_data/sidebars/pmd_sidebar.yml b/docs/_data/sidebars/pmd_sidebar.yml
index 376df38be3..f0a57382be 100644
--- a/docs/_data/sidebars/pmd_sidebar.yml
+++ b/docs/_data/sidebars/pmd_sidebar.yml
@@ -160,24 +160,6 @@ entries:
         - title: Security
           output: web, pdf
           url: /pmd_rules_apex_security.html
-    - title: null
-      output: web, pdf
-      subfolders:
-      - title: Ecmascript Rules
-        output: web, pdf
-        subfolderitems:
-        - title: Index
-          output: web, pdf
-          url: /pmd_rules_ecmascript.html
-        - title: Best Practices
-          output: web, pdf
-          url: /pmd_rules_ecmascript_bestpractices.html
-        - title: Code Style
-          output: web, pdf
-          url: /pmd_rules_ecmascript_codestyle.html
-        - title: Error Prone
-          output: web, pdf
-          url: /pmd_rules_ecmascript_errorprone.html
     - title: null
       output: web, pdf
       subfolders:
@@ -247,6 +229,24 @@ entries:
         - title: Security
           output: web, pdf
           url: /pmd_rules_jsp_security.html
+    - title: null
+      output: web, pdf
+      subfolders:
+      - title: JavaScript Rules
+        output: web, pdf
+        subfolderitems:
+        - title: Index
+          output: web, pdf
+          url: /pmd_rules_ecmascript.html
+        - title: Best Practices
+          output: web, pdf
+          url: /pmd_rules_ecmascript_bestpractices.html
+        - title: Code Style
+          output: web, pdf
+          url: /pmd_rules_ecmascript_codestyle.html
+        - title: Error Prone
+          output: web, pdf
+          url: /pmd_rules_ecmascript_errorprone.html
     - title: null
       output: web, pdf
       subfolders:
diff --git a/pmd-apex/src/main/java/net/sourceforge/pmd/cpd/ApexLanguage.java b/pmd-apex/src/main/java/net/sourceforge/pmd/cpd/ApexLanguage.java
index 0bb7bd7014..5ca6959052 100644
--- a/pmd-apex/src/main/java/net/sourceforge/pmd/cpd/ApexLanguage.java
+++ b/pmd-apex/src/main/java/net/sourceforge/pmd/cpd/ApexLanguage.java
@@ -6,6 +6,8 @@ package net.sourceforge.pmd.cpd;
 
 import java.util.Properties;
 
+import net.sourceforge.pmd.lang.apex.ApexLanguageModule;
+
 public class ApexLanguage extends AbstractLanguage {
 
     public ApexLanguage() {
@@ -13,7 +15,7 @@ public class ApexLanguage extends AbstractLanguage {
     }
 
     public ApexLanguage(Properties properties) {
-        super("Apex", "apex", new ApexTokenizer(), ".cls");
+        super(ApexLanguageModule.NAME, ApexLanguageModule.TERSE_NAME, new ApexTokenizer(), ApexLanguageModule.EXTENSIONS);
         setProperties(properties);
     }
 
diff --git a/pmd-apex/src/main/java/net/sourceforge/pmd/lang/apex/ApexLanguageModule.java b/pmd-apex/src/main/java/net/sourceforge/pmd/lang/apex/ApexLanguageModule.java
index a5fca0cce0..33c9f5b0d6 100644
--- a/pmd-apex/src/main/java/net/sourceforge/pmd/lang/apex/ApexLanguageModule.java
+++ b/pmd-apex/src/main/java/net/sourceforge/pmd/lang/apex/ApexLanguageModule.java
@@ -8,6 +8,7 @@ import static net.sourceforge.pmd.util.CollectionUtil.listOf;
 
 import java.util.List;
 
+import net.sourceforge.pmd.annotation.InternalApi;
 import net.sourceforge.pmd.lang.Language;
 import net.sourceforge.pmd.lang.LanguageModuleBase;
 import net.sourceforge.pmd.lang.LanguageProcessor;
@@ -19,14 +20,18 @@ public class ApexLanguageModule extends LanguageModuleBase {
     public static final String NAME = "Apex";
     public static final String TERSE_NAME = "apex";
 
+    @InternalApi
     public static final List<String> VERSIONS = listOf("52", "53", "54", "55", "56", "57");
+    @InternalApi
+    public static final List<String> EXTENSIONS = listOf("cls", "trigger");
 
     public ApexLanguageModule() {
         super(createMetadata());
     }
 
     private static LanguageMetadata createMetadata() {
-        LanguageMetadata languageMetadata = LanguageMetadata.withId(TERSE_NAME).name(NAME).extensions("cls", "trigger");
+        LanguageMetadata languageMetadata = LanguageMetadata.withId(TERSE_NAME).name(NAME);
+        languageMetadata.extensions(EXTENSIONS.get(0), EXTENSIONS.subList(0, EXTENSIONS.size()).toArray(new String[0]));
         int lastVersion = VERSIONS.size() - 1;
         VERSIONS.subList(0, lastVersion).forEach(languageMetadata::addVersion);
         languageMetadata.addDefaultVersion(VERSIONS.get(lastVersion));
diff --git a/pmd-core/src/main/java/net/sourceforge/pmd/cpd/AbstractLanguage.java b/pmd-core/src/main/java/net/sourceforge/pmd/cpd/AbstractLanguage.java
index 7e08eccf8a..4045ddbf16 100644
--- a/pmd-core/src/main/java/net/sourceforge/pmd/cpd/AbstractLanguage.java
+++ b/pmd-core/src/main/java/net/sourceforge/pmd/cpd/AbstractLanguage.java
@@ -11,6 +11,7 @@ import java.util.Arrays;
 import java.util.List;
 import java.util.Properties;
 import java.util.function.Predicate;
+import java.util.stream.Collectors;
 
 import net.sourceforge.pmd.internal.util.PredicateUtil;
 
@@ -22,11 +23,23 @@ public abstract class AbstractLanguage implements Language {
     private final List<String> extensions;
 
     public AbstractLanguage(String name, String terseName, Tokenizer tokenizer, String... extensions) {
+        this(name, terseName, tokenizer, Arrays.asList(extensions));
+    }
+
+    protected AbstractLanguage(String name, String terseName, Tokenizer tokenizer, List<String> extensions) {
         this.name = name;
         this.terseName = terseName;
         this.tokenizer = tokenizer;
-        this.fileFilter = PredicateUtil.toNormalizedFileFilter(PredicateUtil.getFileExtensionFilter(extensions).or(it -> Files.isDirectory(Paths.get(it))));
-        this.extensions = Arrays.asList(extensions);
+        List<String> extensionsWithDot = extensions.stream().map(e -> {
+            if (e.length() > 0 && e.charAt(0) != '.') {
+                return "." + e;
+            }
+            return e;
+        }).collect(Collectors.toList());
+        this.fileFilter = PredicateUtil.toNormalizedFileFilter(
+                PredicateUtil.getFileExtensionFilter(extensionsWithDot.toArray(new String[0]))
+                        .or(it -> Files.isDirectory(Paths.get(it))));
+        this.extensions = extensionsWithDot;
     }
 
     @Override
diff --git a/pmd-doc/src/test/resources/expected/pmd_sidebar.yml b/pmd-doc/src/test/resources/expected/pmd_sidebar.yml
index b7ce41869c..685cfc5851 100644
--- a/pmd-doc/src/test/resources/expected/pmd_sidebar.yml
+++ b/pmd-doc/src/test/resources/expected/pmd_sidebar.yml
@@ -15,15 +15,6 @@ entries:
         - title: Index
           output: web, pdf
           url: /pmd_rules_apex.html
-    - title: null
-      output: web, pdf
-      subfolders:
-      - title: Ecmascript Rules
-        output: web, pdf
-        subfolderitems:
-        - title: Index
-          output: web, pdf
-          url: /pmd_rules_ecmascript.html
     - title: null
       output: web, pdf
       subfolders:
@@ -54,6 +45,15 @@ entries:
         - title: Index
           output: web, pdf
           url: /pmd_rules_jsp.html
+    - title: null
+      output: web, pdf
+      subfolders:
+      - title: JavaScript Rules
+        output: web, pdf
+        subfolderitems:
+        - title: Index
+          output: web, pdf
+          url: /pmd_rules_ecmascript.html
     - title: null
       output: web, pdf
       subfolders:
diff --git a/pmd-doc/src/test/resources/net/sourceforge/pmd/docs/sidebar.yml b/pmd-doc/src/test/resources/net/sourceforge/pmd/docs/sidebar.yml
index 69435aad61..0b8bcc1128 100644
--- a/pmd-doc/src/test/resources/net/sourceforge/pmd/docs/sidebar.yml
+++ b/pmd-doc/src/test/resources/net/sourceforge/pmd/docs/sidebar.yml
@@ -1,15 +1,3 @@
-- title: null
-  output: web, pdf
-  subfolders:
-  - title: Ecmascript Rules
-    output: web, pdf
-    subfolderitems:
-    - title: Index
-      output: web, pdf
-      url: /pmd_rules_ecmascript.html
-    - title: test
-      output: web, pdf
-      url: /pmd_rules_ecmascript_bestpractices.html
 - title: null
   output: web, pdf
   subfolders:
@@ -25,6 +13,18 @@
     - title: test2
       output: web, pdf
       url: /pmd_rules_java_codestyle.html
+- title: null
+  output: web, pdf
+  subfolders:
+  - title: JavaScript Rules
+    output: web, pdf
+    subfolderitems:
+    - title: Index
+      output: web, pdf
+      url: /pmd_rules_ecmascript.html
+    - title: test
+      output: web, pdf
+      url: /pmd_rules_ecmascript_bestpractices.html
 - title: null
   output: web, pdf
   subfolders:
diff --git a/pmd-html/src/main/java/net/sourceforge/pmd/lang/html/HtmlCpdLanguage.java b/pmd-html/src/main/java/net/sourceforge/pmd/lang/html/HtmlCpdLanguage.java
index 3c6c0fdbde..740acfff6b 100644
--- a/pmd-html/src/main/java/net/sourceforge/pmd/lang/html/HtmlCpdLanguage.java
+++ b/pmd-html/src/main/java/net/sourceforge/pmd/lang/html/HtmlCpdLanguage.java
@@ -11,6 +11,6 @@ import net.sourceforge.pmd.lang.html.ast.HtmlTokenizer;
 public final class HtmlCpdLanguage extends AbstractLanguage {
 
     public HtmlCpdLanguage() {
-        super("HTML", "html", new HtmlTokenizer(), ".html");
+        super(HtmlLanguageModule.NAME, HtmlLanguageModule.TERSE_NAME, new HtmlTokenizer(), HtmlLanguageModule.EXTENSIONS);
     }
 }
diff --git a/pmd-html/src/main/java/net/sourceforge/pmd/lang/html/HtmlLanguageModule.java b/pmd-html/src/main/java/net/sourceforge/pmd/lang/html/HtmlLanguageModule.java
index e93401e190..0743f248b9 100644
--- a/pmd-html/src/main/java/net/sourceforge/pmd/lang/html/HtmlLanguageModule.java
+++ b/pmd-html/src/main/java/net/sourceforge/pmd/lang/html/HtmlLanguageModule.java
@@ -2,9 +2,13 @@
  * BSD-style license; for more info see http://pmd.sourceforge.net/license.html
  */
 
-
 package net.sourceforge.pmd.lang.html;
 
+import static net.sourceforge.pmd.util.CollectionUtil.listOf;
+
+import java.util.List;
+
+import net.sourceforge.pmd.annotation.InternalApi;
 import net.sourceforge.pmd.lang.LanguageRegistry;
 import net.sourceforge.pmd.lang.impl.SimpleLanguageModuleBase;
 
@@ -12,10 +16,12 @@ public final class HtmlLanguageModule extends SimpleLanguageModuleBase {
 
     public static final String NAME = "HTML";
     public static final String TERSE_NAME = "html";
+    @InternalApi
+    public static final List<String> EXTENSIONS = listOf("html", "htm", "xhtml", "xht", "shtml");
 
     public HtmlLanguageModule() {
         super(LanguageMetadata.withId(TERSE_NAME).name(NAME)
-                              .extensions("html", "htm", "xhtml", "xht", "shtml")
+                              .extensions(EXTENSIONS.get(0), EXTENSIONS.subList(0, EXTENSIONS.size()).toArray(new String[0]))
                               .addVersion("4")
                               .addDefaultVersion("5"),
               new HtmlHandler());
diff --git a/pmd-java/src/main/java/net/sourceforge/pmd/cpd/JavaLanguage.java b/pmd-java/src/main/java/net/sourceforge/pmd/cpd/JavaLanguage.java
index 0ff3638c99..2a68ea48a5 100644
--- a/pmd-java/src/main/java/net/sourceforge/pmd/cpd/JavaLanguage.java
+++ b/pmd-java/src/main/java/net/sourceforge/pmd/cpd/JavaLanguage.java
@@ -6,13 +6,15 @@ package net.sourceforge.pmd.cpd;
 
 import java.util.Properties;
 
+import net.sourceforge.pmd.lang.java.JavaLanguageModule;
+
 public class JavaLanguage extends AbstractLanguage {
     public JavaLanguage() {
         this(System.getProperties());
     }
 
     public JavaLanguage(Properties properties) {
-        super("Java", "java", new JavaTokenizer(), ".java");
+        super(JavaLanguageModule.NAME, JavaLanguageModule.TERSE_NAME, new JavaTokenizer(), JavaLanguageModule.EXTENSIONS);
         setProperties(properties);
     }
 
diff --git a/pmd-java/src/main/java/net/sourceforge/pmd/lang/java/JavaLanguageModule.java b/pmd-java/src/main/java/net/sourceforge/pmd/lang/java/JavaLanguageModule.java
index 4bd8bbde05..bc3658ea79 100644
--- a/pmd-java/src/main/java/net/sourceforge/pmd/lang/java/JavaLanguageModule.java
+++ b/pmd-java/src/main/java/net/sourceforge/pmd/lang/java/JavaLanguageModule.java
@@ -4,6 +4,11 @@
 
 package net.sourceforge.pmd.lang.java;
 
+import static net.sourceforge.pmd.util.CollectionUtil.listOf;
+
+import java.util.List;
+
+import net.sourceforge.pmd.annotation.InternalApi;
 import net.sourceforge.pmd.lang.Language;
 import net.sourceforge.pmd.lang.LanguageModuleBase;
 import net.sourceforge.pmd.lang.LanguageProcessor;
@@ -19,9 +24,11 @@ public class JavaLanguageModule extends LanguageModuleBase {
 
     public static final String NAME = "Java";
     public static final String TERSE_NAME = "java";
+    @InternalApi
+    public static final List<String> EXTENSIONS = listOf("java");
 
     public JavaLanguageModule() {
-        super(LanguageMetadata.withId(TERSE_NAME).name(NAME).extensions("java")
+        super(LanguageMetadata.withId(TERSE_NAME).name(NAME).extensions(EXTENSIONS.get(0))
                               .addVersion("1.3")
                               .addVersion("1.4")
                               .addVersion("1.5", "5")
diff --git a/pmd-javascript/src/main/java/net/sourceforge/pmd/cpd/EcmascriptLanguage.java b/pmd-javascript/src/main/java/net/sourceforge/pmd/cpd/EcmascriptLanguage.java
index 2ad5fd6f41..e7edb068fd 100644
--- a/pmd-javascript/src/main/java/net/sourceforge/pmd/cpd/EcmascriptLanguage.java
+++ b/pmd-javascript/src/main/java/net/sourceforge/pmd/cpd/EcmascriptLanguage.java
@@ -4,12 +4,15 @@
 
 package net.sourceforge.pmd.cpd;
 
+import net.sourceforge.pmd.lang.ecmascript.EcmascriptLanguageModule;
+
 /**
  *
  * @author Zev Blut zb@ubit.com
  */
 public class EcmascriptLanguage extends AbstractLanguage {
     public EcmascriptLanguage() {
-        super("JavaScript", "ecmascript", new EcmascriptTokenizer(), ".js");
+        super(EcmascriptLanguageModule.NAME, EcmascriptLanguageModule.TERSE_NAME, new EcmascriptTokenizer(),
+                EcmascriptLanguageModule.EXTENSIONS);
     }
 }
diff --git a/pmd-javascript/src/main/java/net/sourceforge/pmd/lang/ecmascript/EcmascriptLanguageModule.java b/pmd-javascript/src/main/java/net/sourceforge/pmd/lang/ecmascript/EcmascriptLanguageModule.java
index ea4ed73860..e8c56f48c3 100644
--- a/pmd-javascript/src/main/java/net/sourceforge/pmd/lang/ecmascript/EcmascriptLanguageModule.java
+++ b/pmd-javascript/src/main/java/net/sourceforge/pmd/lang/ecmascript/EcmascriptLanguageModule.java
@@ -4,6 +4,11 @@
 
 package net.sourceforge.pmd.lang.ecmascript;
 
+import static net.sourceforge.pmd.util.CollectionUtil.listOf;
+
+import java.util.List;
+
+import net.sourceforge.pmd.annotation.InternalApi;
 import net.sourceforge.pmd.lang.Language;
 import net.sourceforge.pmd.lang.LanguageRegistry;
 import net.sourceforge.pmd.lang.ecmascript.ast.EcmascriptParser;
@@ -14,11 +19,13 @@ import net.sourceforge.pmd.lang.impl.SimpleLanguageModuleBase;
  */
 public class EcmascriptLanguageModule extends SimpleLanguageModuleBase {
 
-    public static final String NAME = "Ecmascript";
+    public static final String NAME = "JavaScript";
     public static final String TERSE_NAME = "ecmascript";
+    @InternalApi
+    public static final List<String> EXTENSIONS = listOf("js");
 
     public EcmascriptLanguageModule() {
-        super(LanguageMetadata.withId(TERSE_NAME).name(NAME).extensions("js")
+        super(LanguageMetadata.withId(TERSE_NAME).name(NAME).extensions(EXTENSIONS.get(0))
                               .addVersion("3")
                               .addVersion("5")
                               .addVersion("6", "ES6", "ES2015")
diff --git a/pmd-jsp/src/main/java/net/sourceforge/pmd/cpd/JSPLanguage.java b/pmd-jsp/src/main/java/net/sourceforge/pmd/cpd/JSPLanguage.java
index c4c480cecc..26b2ef171d 100644
--- a/pmd-jsp/src/main/java/net/sourceforge/pmd/cpd/JSPLanguage.java
+++ b/pmd-jsp/src/main/java/net/sourceforge/pmd/cpd/JSPLanguage.java
@@ -4,8 +4,10 @@
 
 package net.sourceforge.pmd.cpd;
 
+import net.sourceforge.pmd.lang.jsp.JspLanguageModule;
+
 public class JSPLanguage extends AbstractLanguage {
     public JSPLanguage() {
-        super("JSP", "jsp", new JSPTokenizer(), ".jsp", ".jspx", ".jspf", ".tag");
+        super(JspLanguageModule.NAME, JspLanguageModule.TERSE_NAME, new JSPTokenizer(), JspLanguageModule.EXTENSIONS);
     }
 }
diff --git a/pmd-jsp/src/main/java/net/sourceforge/pmd/lang/jsp/JspLanguageModule.java b/pmd-jsp/src/main/java/net/sourceforge/pmd/lang/jsp/JspLanguageModule.java
index d36076551d..33fb67c449 100644
--- a/pmd-jsp/src/main/java/net/sourceforge/pmd/lang/jsp/JspLanguageModule.java
+++ b/pmd-jsp/src/main/java/net/sourceforge/pmd/lang/jsp/JspLanguageModule.java
@@ -4,6 +4,11 @@
 
 package net.sourceforge.pmd.lang.jsp;
 
+import static net.sourceforge.pmd.util.CollectionUtil.listOf;
+
+import java.util.List;
+
+import net.sourceforge.pmd.annotation.InternalApi;
 import net.sourceforge.pmd.lang.impl.SimpleLanguageModuleBase;
 
 /**
@@ -13,10 +18,12 @@ public class JspLanguageModule extends SimpleLanguageModuleBase {
 
     public static final String NAME = "Java Server Pages";
     public static final String TERSE_NAME = "jsp";
+    @InternalApi
+    public static final List<String> EXTENSIONS = listOf("jsp", "jspx", "jspf", "tag");
 
     public JspLanguageModule() {
         super(LanguageMetadata.withId(TERSE_NAME).name(NAME).shortName("JSP")
-                              .extensions("jsp", "jspx", "jspf", "tag")
+                              .extensions(EXTENSIONS.get(0), EXTENSIONS.toArray(new String[0]))
                               .addVersion("2")
                               .addDefaultVersion("3"),
               new JspHandler());
diff --git a/pmd-kotlin/src/main/java/net/sourceforge/pmd/cpd/KotlinLanguage.java b/pmd-kotlin/src/main/java/net/sourceforge/pmd/cpd/KotlinLanguage.java
index 4a14aa766f..1ec0e63349 100644
--- a/pmd-kotlin/src/main/java/net/sourceforge/pmd/cpd/KotlinLanguage.java
+++ b/pmd-kotlin/src/main/java/net/sourceforge/pmd/cpd/KotlinLanguage.java
@@ -4,6 +4,8 @@
 
 package net.sourceforge.pmd.cpd;
 
+import net.sourceforge.pmd.lang.kotlin.KotlinLanguageModule;
+
 /**
  * Language implementation for Kotlin
  */
@@ -13,6 +15,6 @@ public class KotlinLanguage extends AbstractLanguage {
      * Creates a new Kotlin Language instance.
      */
     public KotlinLanguage() {
-        super("Kotlin", "kotlin", new KotlinTokenizer(), ".kt");
+        super(KotlinLanguageModule.NAME, KotlinLanguageModule.TERSE_NAME, new KotlinTokenizer(), KotlinLanguageModule.EXTENSIONS);
     }
 }
diff --git a/pmd-kotlin/src/main/java/net/sourceforge/pmd/lang/kotlin/KotlinLanguageModule.java b/pmd-kotlin/src/main/java/net/sourceforge/pmd/lang/kotlin/KotlinLanguageModule.java
index d82342bc4e..1bdaa924c7 100644
--- a/pmd-kotlin/src/main/java/net/sourceforge/pmd/lang/kotlin/KotlinLanguageModule.java
+++ b/pmd-kotlin/src/main/java/net/sourceforge/pmd/lang/kotlin/KotlinLanguageModule.java
@@ -4,7 +4,12 @@
 
 package net.sourceforge.pmd.lang.kotlin;
 
+import static net.sourceforge.pmd.util.CollectionUtil.listOf;
+
+import java.util.List;
+
 import net.sourceforge.pmd.annotation.Experimental;
+import net.sourceforge.pmd.annotation.InternalApi;
 import net.sourceforge.pmd.lang.impl.SimpleLanguageModuleBase;
 
 /**
@@ -20,11 +25,14 @@ public class KotlinLanguageModule extends SimpleLanguageModuleBase {
     /** The terse name. */
     public static final String TERSE_NAME = "kotlin";
 
+    @InternalApi
+    public static final List<String> EXTENSIONS = listOf("kt", "ktm");
+
     /**
      * Create a new instance of Kotlin Language Module.
      */
     public KotlinLanguageModule() {
-        super(LanguageMetadata.withId(TERSE_NAME).name(NAME).extensions("kt", "ktm")
+        super(LanguageMetadata.withId(TERSE_NAME).name(NAME).extensions(EXTENSIONS.get(0), EXTENSIONS.toArray(new String[0]))
                               .addVersion("1.6")
                               .addDefaultVersion("1.7"),
               new KotlinHandler());
diff --git a/pmd-modelica/src/main/java/net/sourceforge/pmd/cpd/ModelicaLanguage.java b/pmd-modelica/src/main/java/net/sourceforge/pmd/cpd/ModelicaLanguage.java
index 53852955e5..c7c5a58b2c 100644
--- a/pmd-modelica/src/main/java/net/sourceforge/pmd/cpd/ModelicaLanguage.java
+++ b/pmd-modelica/src/main/java/net/sourceforge/pmd/cpd/ModelicaLanguage.java
@@ -8,6 +8,6 @@ import net.sourceforge.pmd.lang.modelica.ModelicaLanguageModule;
 
 public class ModelicaLanguage extends AbstractLanguage {
     public ModelicaLanguage() {
-        super(ModelicaLanguageModule.NAME, ModelicaLanguageModule.TERSE_NAME, new ModelicaTokenizer(), ".mo");
+        super(ModelicaLanguageModule.NAME, ModelicaLanguageModule.TERSE_NAME, new ModelicaTokenizer(), ModelicaLanguageModule.EXTENSIONS);
     }
 }
diff --git a/pmd-modelica/src/main/java/net/sourceforge/pmd/lang/modelica/ModelicaLanguageModule.java b/pmd-modelica/src/main/java/net/sourceforge/pmd/lang/modelica/ModelicaLanguageModule.java
index 290533ba0d..e0c6863a8b 100644
--- a/pmd-modelica/src/main/java/net/sourceforge/pmd/lang/modelica/ModelicaLanguageModule.java
+++ b/pmd-modelica/src/main/java/net/sourceforge/pmd/lang/modelica/ModelicaLanguageModule.java
@@ -4,15 +4,22 @@
 
 package net.sourceforge.pmd.lang.modelica;
 
+import static net.sourceforge.pmd.util.CollectionUtil.listOf;
+
+import java.util.List;
+
+import net.sourceforge.pmd.annotation.InternalApi;
 import net.sourceforge.pmd.lang.impl.SimpleLanguageModuleBase;
 
 public class ModelicaLanguageModule extends SimpleLanguageModuleBase {
     public static final String NAME = "Modelica";
     public static final String TERSE_NAME = "modelica";
+    @InternalApi
+    public static final List<String> EXTENSIONS = listOf("mo");
 
     public ModelicaLanguageModule() {
         super(LanguageMetadata.withId(TERSE_NAME).name(NAME)
-                              .extensions("mo")
+                              .extensions(EXTENSIONS.get(0))
                               .addVersion("3.4")
                               .addDefaultVersion("3.5"),
               new ModelicaHandler());
diff --git a/pmd-plsql/src/main/java/net/sourceforge/pmd/cpd/PLSQLLanguage.java b/pmd-plsql/src/main/java/net/sourceforge/pmd/cpd/PLSQLLanguage.java
index 5331ec9f72..3a744e12ae 100755
--- a/pmd-plsql/src/main/java/net/sourceforge/pmd/cpd/PLSQLLanguage.java
+++ b/pmd-plsql/src/main/java/net/sourceforge/pmd/cpd/PLSQLLanguage.java
@@ -6,22 +6,15 @@ package net.sourceforge.pmd.cpd;
 
 import java.util.Properties;
 
+import net.sourceforge.pmd.lang.plsql.PLSQLLanguageModule;
+
 /**
  *
  * @author Stuart Turton sturton@users.sourceforge.net
  */
 public class PLSQLLanguage extends AbstractLanguage {
     public PLSQLLanguage() {
-        super("PL/SQL", "plsql", new PLSQLTokenizer(),
-                ".sql",
-                ".trg", // Triggers
-                ".prc", ".fnc", // Standalone Procedures and Functions
-                ".pld", // Oracle*Forms
-                ".pls", ".plh", ".plb", // Packages
-                ".pck", ".pks", ".pkh", ".pkb", // Packages
-                ".typ", ".tyb", // Object Types
-                ".tps", ".tpb" // Object Types
-        );
+        super(PLSQLLanguageModule.NAME, PLSQLLanguageModule.TERSE_NAME, new PLSQLTokenizer(), PLSQLLanguageModule.EXTENSIONS);
     }
 
     @Override
diff --git a/pmd-plsql/src/main/java/net/sourceforge/pmd/lang/plsql/PLSQLLanguageModule.java b/pmd-plsql/src/main/java/net/sourceforge/pmd/lang/plsql/PLSQLLanguageModule.java
index 6422362df0..01f262ac4b 100644
--- a/pmd-plsql/src/main/java/net/sourceforge/pmd/lang/plsql/PLSQLLanguageModule.java
+++ b/pmd-plsql/src/main/java/net/sourceforge/pmd/lang/plsql/PLSQLLanguageModule.java
@@ -4,6 +4,11 @@
 
 package net.sourceforge.pmd.lang.plsql;
 
+import static net.sourceforge.pmd.util.CollectionUtil.listOf;
+
+import java.util.List;
+
+import net.sourceforge.pmd.annotation.InternalApi;
 import net.sourceforge.pmd.lang.impl.SimpleLanguageModuleBase;
 
 /**
@@ -13,27 +18,29 @@ public class PLSQLLanguageModule extends SimpleLanguageModuleBase {
 
     public static final String NAME = "PLSQL";
     public static final String TERSE_NAME = "plsql";
+    @InternalApi
+    public static final List<String> EXTENSIONS = listOf(
+            "sql",
+            "trg",  // Triggers
+            "prc", "fnc", // Standalone Procedures and Functions
+            "pld", // Oracle*Forms
+            "pls", "plh", "plb", // Packages
+            "pck", "pks", "pkh", "pkb", // Packages
+            "typ", "tyb", // Object Types
+            "tps", "tpb" // Object Types
+    );
 
     public PLSQLLanguageModule() {
         super(
             LanguageMetadata.withId(TERSE_NAME)
                             .name(NAME)
-                            .extensions(
-                                "sql",
-                                "trg",  // Triggers
-                                "prc", "fnc", // Standalone Procedures and Functions
-                                "pld", // Oracle*Forms
-                                "pls", "plh", "plb", // Packages
-                                "pck", "pks", "pkh", "pkb", // Packages
-                                "typ", "tyb", // Object Types
-                                "tps", "tpb" // Object Types
-                            )
-                           .addVersion("11g")
-                           .addVersion("12c_Release_1", "12.1")
-                           .addVersion("12c_Release_2", "12.2")
-                           .addVersion("18c")
-                           .addVersion("19c")
-                           .addDefaultVersion("21c"),
+                            .extensions(EXTENSIONS.get(0), EXTENSIONS.toArray(new String[0]))
+                            .addVersion("11g")
+                            .addVersion("12c_Release_1", "12.1")
+                            .addVersion("12c_Release_2", "12.2")
+                            .addVersion("18c")
+                            .addVersion("19c")
+                            .addDefaultVersion("21c"),
             new PLSQLHandler()
         );
     }
diff --git a/pmd-scala-modules/pmd-scala-common/src/main/java/net/sourceforge/pmd/cpd/ScalaLanguage.java b/pmd-scala-modules/pmd-scala-common/src/main/java/net/sourceforge/pmd/cpd/ScalaLanguage.java
index fd1f1b6da9..fe1e4c6f03 100644
--- a/pmd-scala-modules/pmd-scala-common/src/main/java/net/sourceforge/pmd/cpd/ScalaLanguage.java
+++ b/pmd-scala-modules/pmd-scala-common/src/main/java/net/sourceforge/pmd/cpd/ScalaLanguage.java
@@ -4,6 +4,8 @@
 
 package net.sourceforge.pmd.cpd;
 
+import net.sourceforge.pmd.lang.scala.ScalaLanguageModule;
+
 /**
  * Language implementation for Scala.
  */
@@ -13,6 +15,6 @@ public class ScalaLanguage extends AbstractLanguage {
      * Creates a new Scala Language instance.
      */
     public ScalaLanguage() {
-        super("Scala", "scala", new ScalaTokenizer(), ".scala");
+        super(ScalaLanguageModule.NAME, ScalaLanguageModule.TERSE_NAME, new ScalaTokenizer(), ScalaLanguageModule.EXTENSIONS);
     }
 }
diff --git a/pmd-scala-modules/pmd-scala-common/src/main/java/net/sourceforge/pmd/lang/scala/ScalaLanguageModule.java b/pmd-scala-modules/pmd-scala-common/src/main/java/net/sourceforge/pmd/lang/scala/ScalaLanguageModule.java
index 1825eec5c6..6bfa00c615 100644
--- a/pmd-scala-modules/pmd-scala-common/src/main/java/net/sourceforge/pmd/lang/scala/ScalaLanguageModule.java
+++ b/pmd-scala-modules/pmd-scala-common/src/main/java/net/sourceforge/pmd/lang/scala/ScalaLanguageModule.java
@@ -4,6 +4,10 @@
 
 package net.sourceforge.pmd.lang.scala;
 
+import static net.sourceforge.pmd.util.CollectionUtil.listOf;
+
+import java.util.List;
+
 import org.checkerframework.checker.nullness.qual.NonNull;
 
 import net.sourceforge.pmd.annotation.InternalApi;
@@ -24,11 +28,14 @@ public class ScalaLanguageModule extends SimpleLanguageModuleBase {
     /** The terse name. */
     public static final String TERSE_NAME = "scala";
 
+    @InternalApi
+    public static final List<String> EXTENSIONS = listOf("scala");
+
     /**
      * Create a new instance of Scala Language Module.
      */
     public ScalaLanguageModule() {
-        super(LanguageMetadata.withId(TERSE_NAME).name(NAME).extensions("scala")
+        super(LanguageMetadata.withId(TERSE_NAME).name(NAME).extensions(EXTENSIONS.get(0))
                               .addVersion("2.10")
                               .addVersion("2.11")
                               .addVersion("2.12")
diff --git a/pmd-swift/src/main/java/net/sourceforge/pmd/cpd/SwiftLanguage.java b/pmd-swift/src/main/java/net/sourceforge/pmd/cpd/SwiftLanguage.java
index 841e0861fd..297f27cf24 100644
--- a/pmd-swift/src/main/java/net/sourceforge/pmd/cpd/SwiftLanguage.java
+++ b/pmd-swift/src/main/java/net/sourceforge/pmd/cpd/SwiftLanguage.java
@@ -4,6 +4,8 @@
 
 package net.sourceforge.pmd.cpd;
 
+import net.sourceforge.pmd.lang.swift.SwiftLanguageModule;
+
 /**
  * Language implementation for Swift
  */
@@ -13,6 +15,6 @@ public class SwiftLanguage extends AbstractLanguage {
      * Creates a new Swift Language instance.
      */
     public SwiftLanguage() {
-        super("Swift", "swift", new SwiftTokenizer(), ".swift");
+        super(SwiftLanguageModule.NAME, SwiftLanguageModule.TERSE_NAME, new SwiftTokenizer(), SwiftLanguageModule.EXTENSIONS);
     }
 }
diff --git a/pmd-swift/src/main/java/net/sourceforge/pmd/lang/swift/SwiftLanguageModule.java b/pmd-swift/src/main/java/net/sourceforge/pmd/lang/swift/SwiftLanguageModule.java
index 5e94c303f0..ac2daf61a5 100644
--- a/pmd-swift/src/main/java/net/sourceforge/pmd/lang/swift/SwiftLanguageModule.java
+++ b/pmd-swift/src/main/java/net/sourceforge/pmd/lang/swift/SwiftLanguageModule.java
@@ -4,6 +4,11 @@
 
 package net.sourceforge.pmd.lang.swift;
 
+import static net.sourceforge.pmd.util.CollectionUtil.listOf;
+
+import java.util.List;
+
+import net.sourceforge.pmd.annotation.InternalApi;
 import net.sourceforge.pmd.lang.impl.SimpleLanguageModuleBase;
 
 /**
@@ -16,12 +21,15 @@ public class SwiftLanguageModule extends SimpleLanguageModuleBase {
     /** The terse name. */
     public static final String TERSE_NAME = "swift";
 
+    @InternalApi
+    public static final List<String> EXTENSIONS = listOf("swift");
+
     /**
      * Create a new instance of Swift Language Module.
      */
     public SwiftLanguageModule() {
         super(LanguageMetadata.withId(TERSE_NAME).name(NAME)
-                              .extensions("swift")
+                              .extensions(EXTENSIONS.get(0))
                               .addVersion("4.2")
                               .addVersion("5.0")
                               .addVersion("5.1")
diff --git a/pmd-visualforce/src/main/java/net/sourceforge/pmd/cpd/VfLanguage.java b/pmd-visualforce/src/main/java/net/sourceforge/pmd/cpd/VfLanguage.java
index 301bfc15c3..5551e91a5d 100644
--- a/pmd-visualforce/src/main/java/net/sourceforge/pmd/cpd/VfLanguage.java
+++ b/pmd-visualforce/src/main/java/net/sourceforge/pmd/cpd/VfLanguage.java
@@ -4,12 +4,14 @@
 
 package net.sourceforge.pmd.cpd;
 
+import net.sourceforge.pmd.lang.vf.VfLanguageModule;
+
 /**
  * @author sergey.gorbaty
  *
  */
 public class VfLanguage extends AbstractLanguage {
     public VfLanguage() {
-        super("VisualForce", "vf", new VfTokenizer(), ".page", ".component");
+        super(VfLanguageModule.NAME, VfLanguageModule.TERSE_NAME, new VfTokenizer(), VfLanguageModule.EXTENSIONS);
     }
 }
diff --git a/pmd-visualforce/src/main/java/net/sourceforge/pmd/lang/vf/VfLanguageModule.java b/pmd-visualforce/src/main/java/net/sourceforge/pmd/lang/vf/VfLanguageModule.java
index 3223c311d2..74f8596ea5 100644
--- a/pmd-visualforce/src/main/java/net/sourceforge/pmd/lang/vf/VfLanguageModule.java
+++ b/pmd-visualforce/src/main/java/net/sourceforge/pmd/lang/vf/VfLanguageModule.java
@@ -4,13 +4,17 @@
 
 package net.sourceforge.pmd.lang.vf;
 
+import static net.sourceforge.pmd.util.CollectionUtil.listOf;
+
+import java.util.List;
+
+import net.sourceforge.pmd.annotation.InternalApi;
 import net.sourceforge.pmd.lang.Language;
 import net.sourceforge.pmd.lang.LanguagePropertyBundle;
 import net.sourceforge.pmd.lang.LanguageRegistry;
 import net.sourceforge.pmd.lang.apex.ApexLanguageModule;
 import net.sourceforge.pmd.lang.impl.SimpleLanguageModuleBase;
 
-
 /**
  * @author sergey.gorbaty
  */
@@ -18,6 +22,8 @@ public class VfLanguageModule extends SimpleLanguageModuleBase {
 
     public static final String NAME = "Salesforce VisualForce";
     public static final String TERSE_NAME = "vf";
+    @InternalApi
+    public static final List<String> EXTENSIONS = listOf("page", "component");
 
     public VfLanguageModule() {
         super(createMetdata(),
@@ -26,7 +32,7 @@ public class VfLanguageModule extends SimpleLanguageModuleBase {
 
     private static LanguageMetadata createMetdata() {
         LanguageMetadata languageMetadata = LanguageMetadata.withId(TERSE_NAME).name(NAME)
-                .extensions("page", "component")
+                .extensions(EXTENSIONS.get(0), EXTENSIONS.toArray(new String[0]))
                 .dependsOnLanguage(ApexLanguageModule.TERSE_NAME);
         // use the same versions as in Apex
         int lastVersion = ApexLanguageModule.VERSIONS.size() - 1;
diff --git a/pmd-xml/src/main/java/net/sourceforge/pmd/lang/xml/XmlLanguageModule.java b/pmd-xml/src/main/java/net/sourceforge/pmd/lang/xml/XmlLanguageModule.java
index 21bf0e22bc..838fac01d0 100644
--- a/pmd-xml/src/main/java/net/sourceforge/pmd/lang/xml/XmlLanguageModule.java
+++ b/pmd-xml/src/main/java/net/sourceforge/pmd/lang/xml/XmlLanguageModule.java
@@ -4,6 +4,11 @@
 
 package net.sourceforge.pmd.lang.xml;
 
+import static net.sourceforge.pmd.util.CollectionUtil.listOf;
+
+import java.util.List;
+
+import net.sourceforge.pmd.annotation.InternalApi;
 import net.sourceforge.pmd.lang.impl.SimpleLanguageModuleBase;
 
 /**
@@ -13,10 +18,12 @@ public class XmlLanguageModule extends SimpleLanguageModuleBase {
 
     public static final String NAME = "XML";
     public static final String TERSE_NAME = "xml";
+    @InternalApi
+    public static final List<String> EXTENSIONS = listOf("xml");
 
     public XmlLanguageModule() {
         super(LanguageMetadata.withId(TERSE_NAME).name(NAME)
-                              .extensions("xml")
+                              .extensions(EXTENSIONS.get(0))
                               .addVersion("1.0")
                               .addDefaultVersion("1.1"),
                 new XmlHandler());
diff --git a/pmd-xml/src/main/java/net/sourceforge/pmd/xml/cpd/XmlLanguage.java b/pmd-xml/src/main/java/net/sourceforge/pmd/xml/cpd/XmlLanguage.java
index 38b38c8eb3..c5c849a248 100644
--- a/pmd-xml/src/main/java/net/sourceforge/pmd/xml/cpd/XmlLanguage.java
+++ b/pmd-xml/src/main/java/net/sourceforge/pmd/xml/cpd/XmlLanguage.java
@@ -5,10 +5,11 @@
 package net.sourceforge.pmd.xml.cpd;
 
 import net.sourceforge.pmd.cpd.AbstractLanguage;
+import net.sourceforge.pmd.lang.xml.XmlLanguageModule;
 
 public class XmlLanguage extends AbstractLanguage {
 
     public XmlLanguage() {
-        super("Xml", "xml", new XmlTokenizer(), ".xml");
+        super(XmlLanguageModule.NAME, XmlLanguageModule.TERSE_NAME, new XmlTokenizer(), XmlLanguageModule.EXTENSIONS);
     }
 }