Fix some details

pmd-apex/src/main/java/net/sourceforge/pmd/lang/apex/ast/ASTApexFile.java

@@ -32,7 +32,7 @@ public final class ASTApexFile extends AbstractApexNode<AstNode> implements Root
                 Map<Integer, String> suppressMap,
                 @NonNull ApexLanguageProcessor apexLang) {
         super(jorjeNode);
-        this.astInfo = new AstInfo<>(task, this, suppressMap);
+        this.astInfo = new AstInfo<>(task, this).withSuppressMap(suppressMap);
         this.multifileAnalysis = apexLang.getMultiFileState();
         this.setRegion(TextRegion.fromOffsetLength(0, task.getTextDocument().getLength()));
     }

pmd-core/src/main/java/net/sourceforge/pmd/lang/LanguageProcessor.java

@@ -10,6 +10,7 @@ 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;
@@ -68,6 +69,11 @@ public interface LanguageProcessor extends AutoCloseable {
         private final LanguageProcessorRegistry lpRegistry;
 
 
+        /**
+         * Create a new task. This constructor is internal and will be
+         * called by PMD.
+         */
+        @InternalApi
         public AnalysisTask(RuleSets rulesets,
                             List<TextFile> files,
                             GlobalAnalysisListener listener,

pmd-core/src/main/java/net/sourceforge/pmd/lang/LanguageRegistry.java

@@ -7,6 +7,7 @@ package net.sourceforge.pmd.lang;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Comparator;
+import java.util.HashSet;
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
@@ -68,18 +69,29 @@ public final class LanguageRegistry implements Iterable<Language> {
     }
 
     /**
-     * Creates a language registry containing the given languages and
-     * their dependencies, fetched from this language registry or the
+     * Creates a language registry containing the given language and
+     * its dependencies, fetched from this language registry or the
      * parameter.
+     *
+     * @throws IllegalStateException If dependencies cannot be fulfilled.
      */
     public LanguageRegistry getDependenciesOf(Language lang) {
-        Set<Language> dependencies =
-            lang.getDependencies().stream()
-                .map(this::getLanguageById)
-                .collect(CollectionUtil.toMutableSet());
-        dependencies.add(lang);
+        Set<Language> result = new HashSet<>();
+        addDepsOrThrow(lang, result);
+        return new LanguageRegistry(result);
+    }
 
-        return new LanguageRegistry(dependencies);
+    private void addDepsOrThrow(Language l, Set<Language> languages) {
+        for (String depId : l.getDependencies()) {
+            Language dep = getLanguageById(depId);
+            if (dep == null) {
+                throw new IllegalStateException(
+                    "Cannot find language " + depId + " in " + this);
+            }
+            if (languages.add(dep)) {
+                addDepsOrThrow(dep, languages);
+            }
+        }
     }
 
     @Override

pmd-core/src/main/java/net/sourceforge/pmd/lang/ast/AstInfo.java

@@ -30,11 +30,7 @@ public final class AstInfo<T extends RootNode> {
 
 
     public AstInfo(ParserTask task, T rootNode) {
-        this(task, rootNode, Collections.emptyMap());
-    }
-
-    public AstInfo(ParserTask task, T rootNode, Map<Integer, String> suppressionComments) {
-        this(task.getTextDocument(), rootNode, task.getLpRegistry(), suppressionComments);
+        this(task.getTextDocument(), rootNode, task.getLpRegistry(), Collections.emptyMap());
     }
 
     private AstInfo(TextDocument textDocument,

pmd-html/src/main/java/net/sourceforge/pmd/lang/html/ast/ASTHtmlDocument.java

@@ -21,7 +21,7 @@ public final class ASTHtmlDocument extends ASTHtmlElement implements RootNode {
                     Parser.ParserTask task,
                     Map<Integer, String> suppressMap) {
         super(document);
-        this.astInfo = new AstInfo<>(task, this, suppressMap);
+        this.astInfo = new AstInfo<>(task, this).withSuppressMap(suppressMap);
     }
 
     @Override

pmd-java/src/main/java/net/sourceforge/pmd/lang/java/ast/JavaParser.java

@@ -55,7 +55,7 @@ public class JavaParser extends JjtreeParserAdapter<ASTCompilationUnit> {
         parser.setPreview(preview);
 
         ASTCompilationUnit root = parser.CompilationUnit();
-        root.setAstInfo(new AstInfo<>(task, root, parser.getSuppressMap()));
+        root.setAstInfo(new AstInfo<>(task, root).withSuppressMap(parser.getSuppressMap()));
 
         LanguageLevelChecker<?> levelChecker =
             new LanguageLevelChecker<>(jdkVersion,

pmd-javascript/src/main/java/net/sourceforge/pmd/lang/ecmascript/ast/EcmascriptParser.java

@@ -70,7 +70,7 @@ public final class EcmascriptParser implements net.sourceforge.pmd.lang.ast.Pars
                 }
             }
         }
-        tree.setAstInfo(new AstInfo<>(task, tree, suppressMap));
+        tree.setAstInfo(new AstInfo<>(task, tree).withSuppressMap(suppressMap));
         return tree;
     }