Propagate @Unmodifiable to enable data-flow inspection to analyze more code

GitOrigin-RevId: 288358515ebebd840b45244cd3d5b251385ff1b8
2026-09-27 10:03:11 +07:00 · 2024-12-03 15:50:19 +00:00
parent c71d8dd467
commit 31185c6576
190 changed files with 375 additions and 24 deletions
@@ -34,6 +34,7 @@ import com.intellij.util.containers.ContainerUtil;
 import org.jetbrains.annotations.Nls;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;

 import java.io.DataInput;
 import java.io.IOException;
@@ -79,6 +80,7 @@ public class InspectionValidatorWrapper implements Validator {
    return ourCompilationThreads.get().booleanValue();
  }

+  @Unmodifiable
  private static List<ProblemDescriptor> runInspectionOnFile(@NotNull PsiFile file, @NotNull LocalInspectionTool inspectionTool) {
    InspectionManager inspectionManager = InspectionManager.getInstance(file.getProject());
    GlobalInspectionContext context = inspectionManager.createNewGlobalContext();
@@ -17,6 +17,7 @@ import com.intellij.packaging.ui.PackagingElementPropertiesPanel;
 import com.intellij.ui.DocumentAdapter;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;

 import javax.swing.*;
 import javax.swing.event.DocumentEvent;
@@ -144,6 +145,7 @@ public abstract class ElementWithManifestPropertiesPanel<E extends CompositeElem
    }
  }

+  @Unmodifiable
  private List<String> getConfiguredClasspath() {
    return StringUtil.split(myClasspathField.getText(), " ");
  }
@@ -70,6 +70,7 @@ public final class ModuleCompilerUtil {
    }));
  }

+  @Unmodifiable
  public static @NotNull List<Chunk<ModuleSourceSet>> computeSourceSetCycles(@NotNull ModulesProvider provider) {
    Graph<ModuleSourceSet> graph = createModuleSourceDependenciesGraph(provider);
    Collection<Chunk<ModuleSourceSet>> chunks = GraphAlgorithms.getInstance().computeStronglyConnectedComponents(graph);
@@ -40,6 +40,7 @@ import com.sun.jdi.request.ClassPrepareRequest;
 import one.util.streamex.StreamEx;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;
 import org.jetbrains.org.objectweb.asm.Opcodes;

 import java.util.*;
@@ -429,6 +430,7 @@ public class PositionManagerImpl implements PositionManager, MultiRequestPositio

  @Override
  @NotNull
+  @Unmodifiable
  public List<ReferenceType> getAllClasses(@NotNull final SourcePosition position) throws NoDataException {
    Set<PsiClass> lineClasses = ReadAction.compute(() -> getLineClasses(position.getFile(), position.getLine()));
    return ContainerUtil.flatMap(lineClasses, aClass -> getClassReferences(aClass, position));
@@ -10,6 +10,7 @@ import com.intellij.openapi.diagnostic.Logger;
 import com.intellij.util.containers.ContainerUtil;
 import com.sun.jdi.ThreadGroupReference;
 import org.jetbrains.annotations.NonNls;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.List;

@@ -59,10 +60,12 @@ public class ThreadGroupReferenceProxyImpl extends ObjectReferenceProxyImpl impl
    getThreadGroupReference().resume();
  }

+  @Unmodifiable
  public List<ThreadReferenceProxyImpl> threads() {
    return ContainerUtil.map(getThreadGroupReference().threads(), getVirtualMachineProxy()::getThreadReferenceProxy);
  }

+  @Unmodifiable
  public List<ThreadGroupReferenceProxyImpl> threadGroups() {
    return ContainerUtil.map(getThreadGroupReference().threadGroups(), getVirtualMachineProxy()::getThreadGroupReferenceProxy);
  }
@@ -254,6 +254,7 @@ public class VirtualMachineProxyImpl implements JdiTimer, VirtualMachineProxy {
  /**
   * @return a list of threadGroupProxies
   */
+  @Unmodifiable
  public List<ThreadGroupReferenceProxyImpl> topLevelThreadGroups() {
    return ContainerUtil.map(getVirtualMachine().topLevelThreadGroups(), this::getThreadGroupReferenceProxy);
  }
@@ -8,6 +8,7 @@ import com.intellij.debugger.engine.evaluation.EvaluationContextImpl;
 import com.intellij.openapi.util.registry.Registry;
 import com.sun.jdi.ObjectReference;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.HashMap;
 import java.util.List;
@@ -29,6 +30,7 @@ public class MemoryAgentPathsToClosestGCRootsProvider implements ReferringObject

  @NotNull
  @Override
+  @Unmodifiable
  public List<ReferringObject> getReferringObjects(@NotNull EvaluationContextImpl evaluationContext,
                                                   @NotNull ObjectReference value,
                                                   long limit) throws EvaluateException {
@@ -50,6 +50,7 @@ public class JavaDebuggerEditorsProvider extends XDebuggerEditorsProviderBase {

  @NotNull
  @Override
+  @Unmodifiable
  public Collection<Language> getSupportedLanguages(@NotNull Project project, @Nullable XSourcePosition sourcePosition) {
    if (sourcePosition != null) {
      return getSupportedLanguages(getContextElement(sourcePosition.getFile(), sourcePosition.getOffset(), project));
@@ -23,6 +23,7 @@ import com.sun.jdi.ReferenceType;
 import com.sun.jdi.request.ClassPrepareRequest;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.List;
 import java.util.Set;
@@ -54,6 +55,7 @@ public interface PositionManager {
   * @see com.intellij.debugger.engine.jdi.VirtualMachineProxy#classesByName
   */
  @NotNull
+  @Unmodifiable
  List<ReferenceType> getAllClasses(@NotNull SourcePosition classPosition) throws NoDataException;

  /**
@@ -18,6 +18,7 @@ import com.sun.jdi.ReferenceType;
 import com.sun.jdi.request.ClassPrepareRequest;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.List;

@@ -49,6 +50,7 @@ public class JavaScratchPositionManager extends PositionManagerImpl{

  @NotNull
  @Override
+  @Unmodifiable
  public List<ReferenceType> getAllClasses(@NotNull SourcePosition position) throws NoDataException {
    checkPosition(position);
    return super.getAllClasses(position);
@@ -20,6 +20,7 @@ import com.intellij.openapi.roots.OrderRootType;
 import com.intellij.openapi.roots.libraries.ui.RootDetector;
 import com.intellij.openapi.vfs.VirtualFile;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.Collection;

@@ -30,6 +31,7 @@ public final class LibraryJavaSourceRootDetector extends RootDetector {

  @NotNull
  @Override
+  @Unmodifiable
  public Collection<VirtualFile> detectRoots(@NotNull VirtualFile rootCandidate,
                                             @NotNull ProgressIndicator progressIndicator) {
    return JavaVfsSourceRootDetectionUtil.suggestRoots(rootCandidate, progressIndicator);
@@ -430,6 +430,7 @@ public abstract class QuickFixFactory {
  public abstract IntentionAction createNotIterableForEachLoopFix(@NotNull PsiExpression expression);

  @NotNull
+  @Unmodifiable
  public abstract List<IntentionAction> createAddAnnotationAttributeNameFixes(@NotNull PsiNameValuePair pair);

  @NotNull
@@ -169,6 +169,7 @@ public interface RefMethod extends RefJavaElement, RefOverridable {

  @NotNull
  @Override
+  @Unmodifiable
  default Collection<? extends RefOverridable> getDerivedReferences() {
    return getDerivedMethods();
  }
@@ -2,6 +2,7 @@
 package com.intellij.codeInspection.reference;

 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.Collection;

@@ -13,6 +14,7 @@ public interface RefOverridable extends RefJavaElement {
   * @return the collection of derived references, e.g. RefMethod may contain at least RefMethod, RefFunctionalExpression as derived reference,
   * RefFunctionalExpression contains nothing.
   */
+  @Unmodifiable
  @NotNull Collection<? extends RefOverridable> getDerivedReferences();

  /**
@@ -264,6 +264,7 @@ class ContractInferenceInterpreter {
  }

  @NotNull
+  @Unmodifiable
  private List<PreContract> visitPolyadic(List<ValueConstraint[]> states, @NotNull LighterASTNode expr) {
    if (firstChildOfType(myTree, expr, JavaTokenType.PLUS) != null) {
      return asPreContracts(ContainerUtil.map(states, s -> new StandardMethodContract(s, returnNotNull())));
@@ -10,6 +10,7 @@ import com.intellij.psi.PsiElement;
 import com.intellij.psi.PsiResourceList;
 import com.intellij.util.containers.FList;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.ArrayList;
 import java.util.List;
@@ -34,6 +35,7 @@ public class EnterFinallyTrap implements DfaControlTransferValue.Trap {
  }

  @Override
+  @Unmodifiable
  public @NotNull List<DfaInstructionState> dispatch(@NotNull DfaMemoryState state,
                                                     @NotNull DataFlowInterpreter interpreter,
                                                     DfaControlTransferValue.@NotNull TransferTarget target,
@@ -68,6 +70,7 @@ public class EnterFinallyTrap implements DfaControlTransferValue.Trap {
    }

    @Override
+    @Unmodifiable
    public @NotNull List<DfaInstructionState> dispatch(@NotNull DfaMemoryState state,
                                                       @NotNull DataFlowInterpreter interpreter,
                                                       DfaControlTransferValue.@NotNull TransferTarget target,
@@ -9,6 +9,7 @@ import com.intellij.codeInspection.dataFlow.value.DfaValue;
 import com.intellij.psi.PsiElement;
 import com.intellij.util.containers.FList;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.List;

@@ -20,6 +21,7 @@ public class InsideFinallyTrap implements DfaControlTransferValue.Trap {
  }

  @Override
+  @Unmodifiable
  public @NotNull List<DfaInstructionState> dispatch(@NotNull DfaMemoryState state,
                                                     @NotNull DataFlowInterpreter interpreter,
                                                     DfaControlTransferValue.@NotNull TransferTarget target,
@@ -6,10 +6,10 @@ import com.intellij.codeInspection.dataFlow.lang.ir.DfaInstructionState;
 import com.intellij.codeInspection.dataFlow.memory.DfaMemoryState;
 import com.intellij.codeInspection.dataFlow.value.DfaControlTransferValue;
 import com.intellij.codeInspection.dataFlow.value.DfaValue;
-import com.intellij.psi.PsiCodeBlock;
 import com.intellij.psi.PsiElement;
 import com.intellij.util.containers.FList;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.List;

@@ -21,6 +21,7 @@ public class InsideInlinedBlockTrap implements DfaControlTransferValue.Trap {
  }

  @Override
+  @Unmodifiable
  public @NotNull List<DfaInstructionState> dispatch(@NotNull DfaMemoryState state,
                                                     @NotNull DataFlowInterpreter interpreter,
                                                     DfaControlTransferValue.@NotNull TransferTarget target,
@@ -9,6 +9,7 @@ import com.intellij.codeInspection.dataFlow.value.DfaControlTransferValue;
 import com.intellij.psi.PsiElement;
 import com.intellij.util.containers.FList;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.List;

@@ -22,6 +23,7 @@ public class TryCatchAllTrap implements DfaControlTransferValue.Trap {
  }

  @Override
+  @Unmodifiable
  public @NotNull List<DfaInstructionState> dispatch(@NotNull DfaMemoryState state,
                                                     @NotNull DataFlowInterpreter interpreter,
                                                     DfaControlTransferValue.@NotNull TransferTarget target,
@@ -34,6 +34,7 @@ import one.util.streamex.EntryStream;
 import one.util.streamex.StreamEx;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.*;

@@ -187,6 +188,7 @@ public final class SuspiciousInvocationHandlerImplementationInspection extends A
    }

    @Override
+    @Unmodifiable
    protected @NotNull List<DfaInstructionState> createInitialInstructionStates(@NotNull PsiElement psiBlock,
                                                                                @NotNull Collection<? extends DfaMemoryState> memStates,
                                                                                @NotNull ControlFlow flow) {
@@ -34,6 +34,7 @@ import com.siyeh.ig.psiutils.CommentTracker;
 import org.jetbrains.annotations.NonNls;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.ArrayList;
 import java.util.Collection;
@@ -91,6 +92,7 @@ public final class VarargParameterInspection extends BaseInspection {
    }

    @NotNull
+    @Unmodifiable
    private static List<PsiElement> getReferences(@NotNull PsiMethod method) {
      if (IntentionPreviewUtils.isIntentionPreviewActive()) {
        return SyntaxTraverser.psiTraverser(method.getContainingFile())
@@ -160,6 +160,7 @@ public final class MakeInferredAnnotationExplicit extends BaseIntentionAction {
                                               () -> doMakeAnnotationExplicit(project, owner, annotations)), file);
  }

+  @Unmodifiable
  private @NotNull List<PsiAnnotation> getAnnotationsToAdd(@NotNull PsiModifierListOwner owner) {
    List<PsiAnnotation> allAnnotations = StreamEx.of(InferredAnnotationsManager.getInstance(owner.getProject()).findInferredAnnotations(owner))
      .remove(DefaultInferredAnnotationProvider::isExperimentalInferredAnnotation)
@@ -567,6 +567,7 @@ public final class JavaCompletionUtil {
    return false;
  }

+  @Unmodifiable
  static @NotNull Iterable<? extends LookupElement> createLookupElements(@NotNull CompletionElement completionElement, @NotNull PsiJavaReference reference) {
    Object completion = completionElement.getElement();
    assert !(completion instanceof LookupElement);
@@ -162,6 +162,7 @@ public final class JavaConstructorCallElement extends LookupElementDecorator<Loo
    return aClass;
  }

+  @Unmodifiable
  static List<? extends LookupElement> wrap(@NotNull JavaPsiClassReferenceElement classItem, @NotNull PsiElement position) {
    PsiClass psiClass = classItem.getObject();
    return wrap(classItem, psiClass, position, () -> JavaPsiFacade.getElementFactory(psiClass.getProject()).createType(psiClass, PsiSubstitutor.EMPTY));
@@ -32,6 +32,7 @@ import static com.intellij.psi.CommonClassNames.*;

 final class StreamConversion {

+  @Unmodifiable
  static List<LookupElement> addToStreamConversion(PsiReferenceExpression ref, CompletionParameters parameters) {
    PsiExpression qualifier = ref.getQualifierExpression();
    if (qualifier == null) return Collections.emptyList();
@@ -28,10 +28,7 @@ import com.intellij.psi.util.PsiUtilCore;
 import com.intellij.util.containers.ContainerUtil;
 import com.siyeh.ig.psiutils.SealedUtils;
 import it.unimi.dsi.fastutil.objects.ReferenceOpenHashSet;
-import org.jetbrains.annotations.ApiStatus;
-import org.jetbrains.annotations.Contract;
-import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.*;

 import java.util.*;

@@ -351,6 +348,7 @@ public final class JavaCompletionProcessor implements PsiScopeProcessor, Element
    }
  }

+  @Unmodifiable
  public Iterable<CompletionElement> getResults() {
    if (mySecondRateResults.size() == myResults.size()) {
      return mySecondRateResults;
@@ -15,6 +15,7 @@ import com.intellij.psi.util.PsiUtil;
 import com.intellij.util.containers.ContainerUtil;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.*;

@@ -129,6 +130,7 @@ public class ImportClassFix extends ImportClassFixBase<PsiJavaCodeReferenceEleme
  }

  @Override
+  @Unmodifiable
  protected @NotNull Collection<PsiClass> filterByContext(@NotNull Collection<PsiClass> candidates, @NotNull PsiJavaCodeReferenceElement referenceElement) {
    if (referenceElement instanceof PsiReferenceExpression) {
      return Collections.emptyList();
@@ -16,6 +16,7 @@ import com.intellij.psi.*;
 import com.intellij.psi.search.GlobalSearchScope;
 import com.intellij.util.IncorrectOperationException;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.List;

@@ -115,6 +116,7 @@ public class GenerateEqualsHandler extends GenerateMembersHandlerBase {
  }

  @Override
+  @Unmodifiable
  protected @NotNull List<? extends GenerationInfo> generateMemberPrototypes(PsiClass aClass, ClassMember[] originalMembers) {
    final boolean useInstanceofToCheckParameterType = CodeInsightSettings.getInstance().USE_INSTANCEOF_ON_EQUALS_PARAMETER;
    final boolean useAccessors = CodeInsightSettings.getInstance().USE_ACCESSORS_IN_EQUALS_HASHCODE;
@@ -269,6 +269,7 @@ public final class OverrideImplementUtil extends OverrideImplementExploreUtil {
    }
  }

+  @Unmodifiable
  public static @NotNull List<PsiGenerationInfo<PsiMethod>> overrideOrImplementMethods(@NotNull PsiClass aClass,
                                                                                       @NotNull Collection<? extends PsiMethodMember> candidates,
                                                                                       boolean toCopyJavaDoc,
@@ -779,6 +779,7 @@ public final class QuickFixFactoryImpl extends QuickFixFactory {
  }

  @Override
+  @Unmodifiable
  public @NotNull List<IntentionAction> createAddAnnotationAttributeNameFixes(@NotNull PsiNameValuePair pair) {
    return AddAnnotationAttributeNameFix.createFixes(pair);
  }
@@ -31,6 +31,7 @@ import com.intellij.util.Processor;
 import com.intellij.util.containers.ContainerUtil;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.*;

@@ -217,6 +218,7 @@ public class JavaFindUsagesHandler extends FindUsagesHandler {
  }

  @Override
+  @Unmodifiable
  public @NotNull Collection<PsiReference> findReferencesToHighlight(final @NotNull PsiElement target, final @NotNull SearchScope searchScope) {
    if (target instanceof PsiMethod) {
      Set<PsiMethod> superTargets = new LinkedHashSet<>();
@@ -19,6 +19,7 @@ import com.intellij.psi.util.PsiUtil;
 import com.intellij.util.LocalTimeCounter;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;

 import java.lang.reflect.Field;
 import java.util.Collections;
@@ -491,6 +492,7 @@ public final class JavaLanguageCodeStyleSettingsProvider extends LanguageCodeSty
    }

    @Override
+    @Unmodifiable
    protected List<String> parseString(@NotNull String string) {
      return CodeStylePropertiesUtil.getValueList(string);
    }
@@ -14,6 +14,7 @@ import com.intellij.psi.PsiManager;
 import com.intellij.psi.PsiPackage;
 import com.intellij.util.ArrayUtil;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.*;

@@ -41,6 +42,7 @@ public class PackageViewProjectNode extends AbstractProjectNode {
  }

  @Override
+  @Unmodifiable
  public @NotNull Collection<AbstractTreeNode<?>> getChildren() {
    if (getSettings().isShowModules()) {
      return modulesAndGroups(moduleDescriptions(myProject));
@@ -40,6 +40,7 @@ import com.intellij.util.containers.ContainerUtil;
 import com.intellij.util.containers.SmartHashSet;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;

 import javax.swing.*;
 import java.io.*;
@@ -329,6 +330,7 @@ public final class JavadocGeneratorRunProfile implements ModuleRunProfile {
      return argsFile;
    }

+    @Unmodifiable
    private @NotNull List<VirtualFile> findSourceRoots(@NotNull Set<Module> modules) {
      OrderEnumerator sourcePathEnumerator = ProjectRootManager.getInstance(myProject).orderEntries(modules);
      if (!myConfiguration.OPTION_INCLUDE_LIBS) {
@@ -340,6 +342,7 @@ public final class JavadocGeneratorRunProfile implements ModuleRunProfile {
      return sourcePathEnumerator.getSourcePathsList().getRootDirs();
    }

+    @Unmodifiable
    private @NotNull List<VirtualFile> findClassRoots(@NotNull Set<Module> modules, @NotNull Sdk jdk) {
      OrderEnumerator classPathEnumerator = ProjectRootManager.getInstance(myProject).orderEntries(modules).withoutModuleSourceEntries();
      if (jdk.getSdkType() instanceof JavaSdk) {
@@ -5,11 +5,13 @@ import com.intellij.codeInsight.daemon.impl.focusMode.FocusModeProvider;
 import com.intellij.openapi.util.Segment;
 import com.intellij.psi.*;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.List;

 public final class JavaFocusModeProvider implements FocusModeProvider {
  @Override
+  @Unmodifiable
  public @NotNull List<? extends Segment> calcFocusZones(@NotNull PsiFile file) {
    return SyntaxTraverser.psiTraverser(file)
      .postOrderDfsTraversal()
@@ -46,6 +46,7 @@ import org.jdom.Element;
 import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;
 import org.jetbrains.concurrency.Promise;
 import org.jetbrains.jps.model.java.JdkVersionDetector;
 import org.jetbrains.jps.model.java.impl.JavaSdkUtil;
@@ -493,6 +494,7 @@ public final class JavaSdkImpl extends JavaSdk {
   * Tries to load the list of modules in the JDK from the 'release' file. Returns null if the 'release' file is not there
   * or doesn't contain the expected information.
   */
+  @Unmodifiable
  private static @Nullable List<String> readModulesFromReleaseFile(@NotNull Path jrtBaseDir) {
    try (InputStream stream = Files.newInputStream(jrtBaseDir.resolve("release"))) {
      Properties p = new Properties();
@@ -19,6 +19,7 @@ import com.intellij.extapi.psi.ASTWrapperPsiElement;
 import com.intellij.lang.ASTNode;
 import com.intellij.spi.parsing.SPIElementTypes;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.List;

@@ -27,6 +28,7 @@ public class SPIClassProvidersElementList extends ASTWrapperPsiElement {
    super(node);
  }
  
+  @Unmodifiable
  public List<SPIClassProviderReferenceElement> getElements() {
    return findChildrenByType(SPIElementTypes.PROVIDER);
  }
@@ -8,6 +8,7 @@ import com.siyeh.ig.psiutils.SwitchUtils;
 import one.util.streamex.StreamEx;
 import org.jetbrains.annotations.Nls;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.List;
 import java.util.Set;
@@ -29,7 +30,7 @@ public final class CreateEnumMissingSwitchBranchesFix extends CreateMissingSwitc
  }

  @Override
-  protected @NotNull Function<PsiSwitchLabelStatementBase, List<String>> getCaseExtractor() {
+  protected @NotNull Function<PsiSwitchLabelStatementBase, @Unmodifiable List<String>> getCaseExtractor() {
    return label -> ContainerUtil.map(SwitchUtils.findEnumConstants(label), PsiEnumConstant::getName);
  }
 }
@@ -10,6 +10,7 @@ import com.siyeh.ig.psiutils.SwitchUtils;
 import org.jetbrains.annotations.Nls;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.*;
 import java.util.function.Function;
@@ -72,7 +73,7 @@ public final class CreateMissingBooleanPrimitiveBranchesFix extends CreateMissin
  }

  @Override
-  protected @NotNull Function<PsiSwitchLabelStatementBase, List<String>> getCaseExtractor() {
+  protected @NotNull Function<PsiSwitchLabelStatementBase, @Unmodifiable List<String>> getCaseExtractor() {
    return label -> {
      PsiCaseLabelElementList list = label.getCaseLabelElementList();
      if (list == null) return Collections.emptyList();
@@ -14,6 +14,7 @@ import com.siyeh.ig.psiutils.VariableNameGenerator;
 import org.jetbrains.annotations.Nls;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.*;
 import java.util.function.Function;
@@ -48,7 +49,7 @@ public final class CreateMissingDeconstructionRecordClassBranchesFix extends Cre
  }

  @Override
-  protected @NotNull Function<PsiSwitchLabelStatementBase, List<String>> getCaseExtractor() {
+  protected @NotNull Function<PsiSwitchLabelStatementBase, @Unmodifiable List<String>> getCaseExtractor() {
    return label -> {
      PsiCaseLabelElementList list = label.getCaseLabelElementList();
      if (list == null) return Collections.emptyList();
@@ -50,5 +50,5 @@ public abstract class CreateMissingSwitchBranchesFix extends BaseSwitchFix {

  @Unmodifiable
  protected abstract @NotNull List<String> getAllNames(@NotNull PsiClass aClass, @NotNull PsiSwitchBlock switchBlock);
-  protected abstract @NotNull Function<PsiSwitchLabelStatementBase, List<String>> getCaseExtractor();
+  protected abstract @NotNull Function<PsiSwitchLabelStatementBase, @Unmodifiable List<String>> getCaseExtractor();
 }
@@ -88,7 +88,7 @@ public class CreateSealedClassMissingSwitchBranchesFix extends CreateMissingSwit
  }

  @Override
-  protected @NotNull Function<PsiSwitchLabelStatementBase, List<String>> getCaseExtractor() {
+  protected @NotNull Function<PsiSwitchLabelStatementBase, @Unmodifiable List<String>> getCaseExtractor() {
    return label -> {
      PsiCaseLabelElementList list = label.getCaseLabelElementList();
      if (list == null) return Collections.emptyList();
@@ -9,12 +9,14 @@ import com.intellij.psi.PsiLiteralExpression;
 import com.intellij.psi.SyntaxTraverser;
 import com.intellij.util.Function;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.Collection;
 import java.util.List;

 public final class StringFormatUsageSearcher implements UsageSearcher {
  @Override
+  @Unmodifiable
  public @NotNull Collection<? extends Usage> collectImmediateResults(@NotNull UsageSearchParameters parameters) {
    SearchTarget target = parameters.getTarget();
    if (target instanceof StringFormatSymbolReferenceProvider.JavaFormatArgumentSymbol symbol) {
@@ -26,6 +28,7 @@ public final class StringFormatUsageSearcher implements UsageSearcher {
    return List.of();
  }

+  @Unmodifiable
  private static @NotNull List<Usage> getFormatUsages(@NotNull Symbol symbol,
                                                      @NotNull PsiExpression expression,
                                                      @NotNull PsiExpression arg,
@@ -35,6 +35,7 @@ import org.jdom.Element;
 import org.jetbrains.annotations.NonNls;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.*;

@@ -242,6 +243,7 @@ public final class IfCanBeSwitchInspection extends BaseInspection {
    }
  }

+  @Unmodifiable
  private static @NotNull List<PsiTypeCastExpression> getRelatesCastExpressions(PsiElement expression, PsiInstanceOfExpression targetInstanceOf) {
    return SyntaxTraverser.psiTraverser(expression)
      .filter(PsiTypeCastExpression.class)
@@ -54,10 +54,11 @@ public final class CreateSwitchBranchesUtil {
   *                      thus some kind of normalization could be necessary.
   * @return a list of created branches
   */
+  @Unmodifiable
  public static List<PsiSwitchLabelStatementBase> createMissingBranches(@NotNull PsiSwitchBlock switchBlock,
                                                                        @NotNull List<String> allNames,
                                                                        @NotNull @Unmodifiable Collection<String> missingNames,
-                                                                        @NotNull Function<? super PsiSwitchLabelStatementBase, ? extends List<String>> caseExtractor) {
+                                                                        @NotNull Function<? super PsiSwitchLabelStatementBase, ? extends @Unmodifiable List<String>> caseExtractor) {
    final JavaCodeStyleManager javaCodeStyleManager = JavaCodeStyleManager.getInstance(switchBlock.getProject());
    boolean isRuleBasedFormat = SwitchUtils.isRuleFormatSwitch(switchBlock);
    final PsiCodeBlock body = switchBlock.getBody();
@@ -2,6 +2,7 @@
 package com.intellij.lang.jvm.annotation;

 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.List;

@@ -11,5 +12,6 @@ import java.util.List;
 public interface JvmAnnotationArrayValue extends JvmAnnotationAttributeValue {

  @NotNull
+  @Unmodifiable
  List<JvmAnnotationAttributeValue> getValues();
 }
@@ -10,6 +10,7 @@ import com.intellij.psi.util.PsiUtil;
 import org.jetbrains.annotations.Contract;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;

 import static com.intellij.util.containers.ContainerUtil.mapNotNull;

@@ -21,6 +22,7 @@ public final class JvmUtil {
  private JvmUtil() {}

  @NotNull
+  @Unmodifiable
  static Iterable<JvmClass> resolveClasses(JvmReferenceType @NotNull [] types) {
    return mapNotNull(types, JvmUtil::resolveClass);
  }
@@ -7,6 +7,7 @@ import com.intellij.lang.jvm.JvmEnumField;
 import com.intellij.lang.jvm.annotation.*;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.List;

@@ -99,6 +100,7 @@ class PsiAnnotationArrayValue extends PsiAnnotationAttributeValue<PsiArrayInitia

  @NotNull
  @Override
+  @Unmodifiable
  public List<JvmAnnotationAttributeValue> getValues() {
    return map(myElement.getInitializers(), PsiJvmConversionHelper::getAnnotationAttributeValue);
  }
@@ -13,6 +13,7 @@ import com.intellij.util.IncorrectOperationException;
 import org.jetbrains.annotations.NonNls;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.Collection;
 import java.util.List;
@@ -273,6 +274,7 @@ public interface PsiClass
   * @return the found methods and their substitutors, or an empty list if no methods are found.
   */
  @NotNull
+  @Unmodifiable
  List<Pair<PsiMethod, PsiSubstitutor>> findMethodsAndTheirSubstitutorsByName(@NonNls @NotNull String name, boolean checkBases);

  /**
@@ -282,6 +284,7 @@ public interface PsiClass
   * @return the list of methods and their substitutors
   */
  @NotNull
+  @Unmodifiable
  List<Pair<PsiMethod, PsiSubstitutor>> getAllMethodsAndTheirSubstitutors();

  /**
@@ -167,6 +167,7 @@ public class PropertyUtilBase {
  }

  @NotNull
+  @Unmodifiable
  public static List<PsiMethod> getAccessors(@NotNull final PsiClass psiClass, final String propertyName) {
    return getAccessors(psiClass, propertyName, false, ONLY_PUBLIC);
  }
@@ -159,6 +159,7 @@ public final class PsiClassImplUtil {
           : ContainerUtil.filter(type.getMembers(aClass), member -> name.equals(member.getName()));
  }

+  @Unmodifiable
  public static @NotNull <T extends PsiMember> List<Pair<T, PsiSubstitutor>> getAllWithSubstitutorsByMap(@NotNull PsiClass aClass, @NotNull MemberType type) {
    return withSubstitutors(aClass, getMap(aClass).getAllMembers(type, null));
  }
@@ -923,6 +924,7 @@ public final class PsiClassImplUtil {
    return resolved;
  }

+  @Unmodifiable
  public static @NotNull List<Pair<PsiMethod, PsiSubstitutor>> findMethodsAndTheirSubstitutorsByName(@NotNull PsiClass psiClass,
                                                                                                     @NotNull String name,
                                                                                                     boolean checkBases) {
@@ -31,6 +31,7 @@ import com.intellij.util.containers.ContainerUtil;
 import org.jetbrains.annotations.NonNls;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;

 import javax.swing.*;
 import java.util.*;
@@ -269,11 +270,13 @@ public class ClsClassImpl extends ClsMemberImpl<PsiClassStub<?>> implements PsiE
  }

  @Override
+  @Unmodifiable
  public @NotNull List<Pair<PsiMethod, PsiSubstitutor>> findMethodsAndTheirSubstitutorsByName(@NotNull String name, boolean checkBases) {
    return PsiClassImplUtil.findMethodsAndTheirSubstitutorsByName(this, name, checkBases);
  }

  @Override
+  @Unmodifiable
  public @NotNull List<Pair<PsiMethod, PsiSubstitutor>> getAllMethodsAndTheirSubstitutors() {
    return PsiClassImplUtil.getAllWithSubstitutorsByMap(this, PsiClassImplUtil.MemberType.METHOD);
  }
@@ -21,6 +21,7 @@ import com.intellij.util.IncorrectOperationException;
 import com.intellij.util.containers.ContainerUtil;
 import org.jetbrains.annotations.NonNls;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Unmodifiable;

 import javax.swing.*;
 import java.util.Collection;
@@ -85,11 +86,13 @@ public class ClsTypeParameterImpl extends ClsRepositoryPsiElement<PsiTypeParamet
  }

  @Override
+  @Unmodifiable
  public @NotNull List<Pair<PsiMethod, PsiSubstitutor>> findMethodsAndTheirSubstitutorsByName(@NotNull String name, boolean checkBases) {
    return PsiClassImplUtil.findMethodsAndTheirSubstitutorsByName(this, name, checkBases);
  }

  @Override
+  @Unmodifiable
  public @NotNull List<Pair<PsiMethod, PsiSubstitutor>> getAllMethodsAndTheirSubstitutors() {
    return PsiClassImplUtil.getAllWithSubstitutorsByMap(this, PsiClassImplUtil.MemberType.METHOD);
  }
@@ -14,6 +14,7 @@ import com.intellij.util.IncorrectOperationException;
 import org.jetbrains.annotations.NonNls;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.Collection;
 import java.util.List;
@@ -206,11 +207,13 @@ public abstract class AbstractLightClass extends LightElement implements PsiClas
  }

  @Override
+  @Unmodifiable
  public @NotNull List<Pair<PsiMethod, PsiSubstitutor>> findMethodsAndTheirSubstitutorsByName(@NonNls @NotNull String name, boolean checkBases) {
    return PsiClassImplUtil.findMethodsAndTheirSubstitutorsByName(this, name, checkBases);
  }

  @Override
+  @Unmodifiable
  public @NotNull List<Pair<PsiMethod, PsiSubstitutor>> getAllMethodsAndTheirSubstitutors() {
    return PsiClassImplUtil.getAllWithSubstitutorsByMap(this, PsiClassImplUtil.MemberType.METHOD);
  }
@@ -16,6 +16,7 @@ import com.intellij.util.IncorrectOperationException;
 import org.jetbrains.annotations.NonNls;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.Collection;
 import java.util.List;
@@ -152,11 +153,13 @@ public abstract class LightPsiClassBase extends LightElement implements PsiClass
  }

  @Override
+  @Unmodifiable
  public @NotNull List<Pair<PsiMethod, PsiSubstitutor>> findMethodsAndTheirSubstitutorsByName(@NonNls @NotNull String name, boolean checkBases) {
    return PsiClassImplUtil.findMethodsAndTheirSubstitutorsByName(this, name, checkBases);
  }

  @Override
+  @Unmodifiable
  public @NotNull List<Pair<PsiMethod, PsiSubstitutor>> getAllMethodsAndTheirSubstitutors() {
    return PsiClassImplUtil.getAllWithSubstitutorsByMap(this, PsiClassImplUtil.MemberType.METHOD);
  }
@@ -29,6 +29,7 @@ import com.intellij.util.IncorrectOperationException;
 import com.intellij.util.containers.ContainerUtil;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;

 import javax.swing.*;
 import java.util.*;
@@ -361,11 +362,13 @@ public class PsiClassImpl extends JavaStubPsiElement<PsiClassStub<?>> implements
  }

  @Override
+  @Unmodifiable
  public @NotNull List<Pair<PsiMethod, PsiSubstitutor>> findMethodsAndTheirSubstitutorsByName(@NotNull String name, boolean checkBases) {
    return PsiClassImplUtil.findMethodsAndTheirSubstitutorsByName(this, name, checkBases);
  }

  @Override
+  @Unmodifiable
  public @NotNull List<Pair<PsiMethod, PsiSubstitutor>> getAllMethodsAndTheirSubstitutors() {
    return PsiClassImplUtil.getAllWithSubstitutorsByMap(this, PsiClassImplUtil.MemberType.METHOD);
  }
@@ -22,6 +22,7 @@ import com.intellij.psi.util.PsiUtil;
 import com.intellij.util.IncorrectOperationException;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;

 import javax.swing.*;
 import java.util.Arrays;
@@ -172,11 +173,13 @@ public class PsiImplicitClassImpl extends JavaStubPsiElement<PsiClassStub<?>> im
  }

  @Override
+  @Unmodifiable
  public @NotNull List<Pair<PsiMethod, PsiSubstitutor>> findMethodsAndTheirSubstitutorsByName(@NotNull String name, boolean checkBases) {
    return PsiClassImplUtil.findMethodsAndTheirSubstitutorsByName(this, name, checkBases);
  }

  @Override
+  @Unmodifiable
  public @NotNull List<Pair<PsiMethod, PsiSubstitutor>> getAllMethodsAndTheirSubstitutors() {
    return PsiClassImplUtil.getAllWithSubstitutorsByMap(this, PsiClassImplUtil.MemberType.METHOD);
  }
@@ -16,6 +16,7 @@ import com.intellij.psi.util.PsiUtil;
 import com.intellij.util.IncorrectOperationException;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.Collection;
 import java.util.List;
@@ -179,11 +180,13 @@ public class PsiJShellRootClassImpl extends ASTWrapperPsiElement implements PsiJ
  }

  @Override
+  @Unmodifiable
  public @NotNull List<Pair<PsiMethod, PsiSubstitutor>> findMethodsAndTheirSubstitutorsByName(@NotNull String name, boolean checkBases) {
    return PsiClassImplUtil.findMethodsAndTheirSubstitutorsByName(this, name, checkBases);
  }

  @Override
+  @Unmodifiable
  public @NotNull List<Pair<PsiMethod, PsiSubstitutor>> getAllMethodsAndTheirSubstitutors() {
    return PsiClassImplUtil.getAllWithSubstitutorsByMap(this, PsiClassImplUtil.MemberType.METHOD);
  }
@@ -20,6 +20,7 @@ import com.intellij.util.SmartList;
 import com.intellij.util.containers.ContainerUtil;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.ArrayList;
 import java.util.Collection;
@@ -67,6 +68,7 @@ public class PsiCatchSectionImpl extends CompositePsiElement implements PsiCatch
    );
  }

+  @Unmodifiable
  private List<PsiType> computePreciseCatchTypes(final @Nullable PsiParameter parameter) {
    if (parameter == null) {
      return ContainerUtil.emptyList();
@@ -21,6 +21,7 @@ import com.intellij.psi.util.PsiUtil;
 import com.intellij.util.IncorrectOperationException;
 import org.jetbrains.annotations.NonNls;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Unmodifiable;

 import javax.swing.*;
 import java.util.Collection;
@@ -86,11 +87,13 @@ public class PsiTypeParameterImpl extends JavaStubPsiElement<PsiTypeParameterStu
  }

  @Override
+  @Unmodifiable
  public @NotNull List<Pair<PsiMethod, PsiSubstitutor>> findMethodsAndTheirSubstitutorsByName(@NotNull String name, boolean checkBases) {
    return PsiClassImplUtil.findMethodsAndTheirSubstitutorsByName(this, name, checkBases);
  }

  @Override
+  @Unmodifiable
  public @NotNull List<Pair<PsiMethod, PsiSubstitutor>> getAllMethodsAndTheirSubstitutors() {
    return PsiClassImplUtil.getAllWithSubstitutorsByMap(this, PsiClassImplUtil.MemberType.METHOD);
  }
@@ -18,6 +18,7 @@ import com.intellij.psi.PsiMember;
 import com.intellij.psi.SyntaxTraverser;
 import org.jetbrains.annotations.NonNls;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.Collections;
 import java.util.List;
@@ -28,6 +29,7 @@ public class JavaLambdaNodeProvider implements FileStructureNodeProvider<JavaLam

  @NotNull
  @Override
+  @Unmodifiable
  public List<JavaLambdaTreeElement> provideNodes(@NotNull TreeElement node) {
    if (!(node instanceof PsiTreeElementBase)) {
      return Collections.emptyList();
@@ -27,6 +27,7 @@ package org.jetbrains.lang.manifest.psi;
 import com.intellij.psi.PsiNamedElement;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.List;

@@ -51,5 +52,6 @@ public interface Header extends PsiNamedElement {
   * Returns a list of all header value elements.
   */
  @NotNull
+  @Unmodifiable
  List<HeaderValue> getHeaderValues();
 }
@@ -27,6 +27,7 @@ package org.jetbrains.lang.manifest.psi;
 import com.intellij.psi.PsiFile;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.List;

@@ -38,6 +39,7 @@ public interface ManifestFile extends PsiFile {
   * Returns all sections of the file.
   */
  @NotNull
+  @Unmodifiable
  List<Section> getSections();

  /**
@@ -50,6 +52,7 @@ public interface ManifestFile extends PsiFile {
   * Returns all headers from the main section in this file.
   */
  @NotNull
+  @Unmodifiable
  List<Header> getHeaders();

  /**
@@ -32,6 +32,7 @@ import com.intellij.psi.util.PsiTreeUtil;
 import com.intellij.util.IncorrectOperationException;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;
 import org.jetbrains.lang.manifest.psi.*;

 import java.util.List;
@@ -72,6 +73,7 @@ public class HeaderImpl extends ASTWrapperPsiElement implements Header {

  @NotNull
  @Override
+  @Unmodifiable
  public List<HeaderValue> getHeaderValues() {
    return PsiTreeUtil.getChildrenOfTypeAsList(this, HeaderValue.class);
  }
@@ -30,6 +30,7 @@ import com.intellij.psi.FileViewProvider;
 import com.intellij.psi.util.PsiTreeUtil;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;
 import org.jetbrains.lang.manifest.ManifestFileType;
 import org.jetbrains.lang.manifest.ManifestLanguage;
 import org.jetbrains.lang.manifest.psi.Header;
@@ -54,6 +55,7 @@ public class ManifestFileImpl extends PsiFileBase implements ManifestFile {

  @NotNull
  @Override
+  @Unmodifiable
  public List<Section> getSections() {
    return PsiTreeUtil.getChildrenOfTypeAsList(this, Section.class);
  }
@@ -66,6 +68,7 @@ public class ManifestFileImpl extends PsiFileBase implements ManifestFile {

  @NotNull
  @Override
+  @Unmodifiable
  public List<Header> getHeaders() {
    return PsiTreeUtil.getChildrenOfTypeAsList(getFirstChild(), Header.class);
  }
@@ -214,6 +214,7 @@ public abstract class DaemonAnalyzerTestCase extends JavaCodeInsightTestCase {
  }

  @NotNull
+  @Unmodifiable
  protected Collection<HighlightInfo> doDoTest(boolean checkWarnings, boolean checkInfos) {
    return doDoTest(checkWarnings, checkInfos, false);
  }
@@ -282,16 +283,19 @@ public abstract class DaemonAnalyzerTestCase extends JavaCodeInsightTestCase {
  }

  @NotNull
+  @Unmodifiable
  protected final List<HighlightInfo> highlightErrors() {
    return doHighlighting(HighlightSeverity.ERROR);
  }

  @NotNull
+  @Unmodifiable
  protected final List<HighlightInfo> doHighlighting(@NotNull HighlightSeverity minSeverity) {
    return filter(doHighlighting(), minSeverity);
  }

  @NotNull
+  @Unmodifiable
  protected final List<HighlightInfo> doHighlighting() {
    PsiDocumentManager.getInstance(myProject).commitAllDocuments();

@@ -23,6 +23,7 @@ import it.unimi.dsi.fastutil.ints.IntList;
 import org.jetbrains.annotations.NonNls;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.Collection;
 import java.util.List;
@@ -120,11 +121,13 @@ public abstract class LightDaemonAnalyzerTestCase extends LightJavaCodeInsightTe
  }

  @NotNull
+  @Unmodifiable
  protected List<HighlightInfo> highlightErrors() {
    return doHighlighting(HighlightSeverity.ERROR);
  }

  @NotNull
+  @Unmodifiable
  protected List<HighlightInfo> doHighlighting() {
    PsiDocumentManager.getInstance(getProject()).commitAllDocuments();

@@ -150,6 +153,7 @@ public abstract class LightDaemonAnalyzerTestCase extends LightJavaCodeInsightTe
    return annotatedWith(DaemonAnalyzerTestCase.CanChangeDocumentDuringHighlighting.class);
  }

+  @Unmodifiable
  protected List<HighlightInfo> doHighlighting(HighlightSeverity minSeverity) {
    return DaemonAnalyzerTestCase.filter(doHighlighting(), minSeverity);
  }
@@ -28,6 +28,7 @@ import com.intellij.util.ui.UIUtil;
 import one.util.streamex.StreamEx;
 import org.jetbrains.annotations.NonNls;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Unmodifiable;

 import java.io.File;
 import java.nio.charset.StandardCharsets;
@@ -315,12 +316,14 @@ public abstract class LightQuickFixTestCase extends LightDaemonAnalyzerTestCase

      @NotNull
      @Override
+      @Unmodifiable
      public List<HighlightInfo> doHighlighting() {
        return LightQuickFixTestCase.this.doHighlighting();
      }

      @NotNull
      @Override
+      @Unmodifiable
      public List<IntentionAction> getAvailableActions() {
        return LightQuickFixTestCase.this.getAvailableActions();
      }
@@ -347,12 +350,14 @@ public abstract class LightQuickFixTestCase extends LightDaemonAnalyzerTestCase
    };
  }

+  @Unmodifiable
  protected List<IntentionAction> getAvailableActions() {
    doHighlighting();
    return getAvailableActions(getEditor(), getFile());
  }

  @NotNull
+  @Unmodifiable
  public static List<IntentionAction> getAvailableActions(@NotNull Editor editor, @NotNull PsiFile file) {
    return CodeInsightTestFixtureImpl.getAvailableIntentions(editor, file);
  }
@@ -20,6 +20,7 @@ import com.intellij.codeInsight.intention.IntentionAction;
 import com.intellij.openapi.project.Project;
 import com.intellij.psi.PsiFile;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.List;

@@ -57,9 +58,11 @@ public interface QuickFixTestCase {
  void checkPreviewAndInvoke(@NotNull IntentionAction action, @NotNull String previewFilePath);

  @NotNull
+  @Unmodifiable
  List<HighlightInfo> doHighlighting();

  @NotNull
+  @Unmodifiable
  List<IntentionAction> getAvailableActions();

  void bringRealEditorBack();
@@ -31,6 +31,7 @@ public class MockPsiClassType extends MockPsiReferenceType implements ClassType
  }

  @Override
+  @Unmodifiable
  public List<InterfaceType> allInterfaces() {
    return interfaces();
  }
@@ -6,11 +6,13 @@ import com.intellij.psi.controlFlow.*;
 import com.intellij.psi.util.PsiTreeUtil;
 import com.intellij.util.containers.ContainerUtil;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.Collection;
 import java.util.List;

 final class TypeConversionRuleUtil {
+  @Unmodifiable
  static List<PsiVariable> getVariablesToMakeFinal(@NotNull PsiExpression expression) {
    final ControlFlow controlFlow;
    try {
@@ -4,6 +4,7 @@ package com.intellij.codeInsight.intention;
 import com.intellij.openapi.editor.Editor;
 import com.intellij.psi.PsiFile;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.List;

@@ -49,6 +50,7 @@ public interface CustomizableIntentionActionDelegate extends IntentionActionDele
  }

  @Override
+  @Unmodifiable
  default @NotNull List<RangeToHighlight> getRangesToHighlight(@NotNull Editor editor, @NotNull PsiFile file) {
    IntentionAction action = IntentionActionDelegate.unwrap(getDelegate());
    if (action instanceof CustomizableIntentionAction) {
@@ -92,5 +92,6 @@ public interface Lookup {

  boolean isSelectionTouched();

+  @Unmodifiable
  List<String> getAdvertisements();
 }
@@ -7,6 +7,7 @@ import com.intellij.openapi.util.ClassConditionKey;
 import com.intellij.psi.PsiElement;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.Set;

@@ -42,6 +43,7 @@ public abstract class LookupElementDecorator<T extends LookupElement> extends Lo
  }

  @Override
+  @Unmodifiable
  public Set<String> getAllLookupStrings() {
    return myDelegate.getAllLookupStrings();
  }
@@ -198,6 +198,7 @@ public abstract class InspectionProfileEntry implements BatchSuppressableTool, O
    return alternativeId != null && !alternativeId.equals(toolId) && suppressor.isSuppressedFor(element, alternativeId);
  }

+  @Unmodifiable
  public static @NotNull Collection<InspectionSuppressor> getSuppressors(@NotNull PsiElement element) {
    PsiFile file = element.getContainingFile();
    if (file == null) {
@@ -9,6 +9,7 @@ import org.intellij.lang.annotations.Language;
 import org.jetbrains.annotations.NonNls;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.Arrays;
 import java.util.List;
@@ -214,6 +215,7 @@ public abstract class LocalInspectionTool extends InspectionProfileEntry impleme
  public void inspectionFinished(@NotNull LocalInspectionToolSession session, @NotNull ProblemsHolder problemsHolder) {
  }

+  @Unmodifiable
  public @NotNull List<ProblemDescriptor> processFile(@NotNull PsiFile file, @NotNull InspectionManager manager) {
    return manager.defaultProcessFile(this, file);
  }
@@ -28,6 +28,7 @@ import com.intellij.util.containers.ContainerUtil;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import org.jetbrains.annotations.TestOnly;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.List;

@@ -236,6 +237,7 @@ public final class QuickFixWrapper implements IntentionAction, PriorityAction, C
  }

  @Override
+  @Unmodifiable
  public @NotNull List<@NotNull RangeToHighlight> getRangesToHighlight(@NotNull Editor editor, @NotNull PsiFile file) {
    return myFix.getRangesToHighlight(file.getProject(), myDescriptor);
  }
@@ -4,6 +4,7 @@ package com.intellij.openapi.vfs.newvfs;
 import com.intellij.openapi.vfs.VirtualFile;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;

 import java.io.IOException;
 import java.io.InputStream;
@@ -34,6 +35,7 @@ public interface FileSystemInterface {
   * Returns all virtual files under which the given path is known in the VFS, starting with virtual file for the passed path.
   * Please note, that it is guaranteed to find all aliases only if path is canonical.
   */
+  @Unmodifiable
  default @NotNull Iterable<@NotNull VirtualFile> findCachedFilesForPath(@NotNull String path) {
    return Collections.emptyList();
  }
@@ -10,6 +10,7 @@ import com.intellij.util.ProcessingContext;
 import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.IdentityHashMap;
 import java.util.List;
@@ -64,6 +65,7 @@ public class CachingComparingClassifier extends ComparingClassifier<LookupElemen
  }

  @Override
+  @Unmodifiable
  public @NotNull List<Pair<LookupElement, Object>> getSortingWeights(@NotNull Iterable<? extends LookupElement> items, @NotNull ProcessingContext context) {
    checkPrefixChanged(context);
    return super.getSortingWeights(items, context);
@@ -60,10 +60,12 @@ public final class DfaControlTransferValue extends DfaValue {
    return indices.toIntArray();
  }

+  @Unmodifiable
  public @NotNull List<DfaInstructionState> dispatch(@NotNull DfaMemoryState state, @NotNull DataFlowInterpreter interpreter) {
    return dispatch(state, interpreter, target, traps);
  }

+  @Unmodifiable
  public static @NotNull List<DfaInstructionState> dispatch(@NotNull DfaMemoryState state,
                                                            @NotNull DataFlowInterpreter interpreter,
                                                            @NotNull TransferTarget target,
@@ -63,6 +63,7 @@ public abstract class PerFileMappingsBase<T> implements PersistentStateComponent
  protected @Nullable Project getProject() { return myProject; }

  @Override
+  @Unmodifiable
  public @NotNull Map<VirtualFile, T> getMappings() {
    synchronized (myMappings) {
      ensureStateLoaded();
@@ -5,6 +5,7 @@ package com.intellij.lang;
 import com.intellij.openapi.vfs.VirtualFile;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.Map;

@@ -14,6 +15,7 @@ import java.util.Map;
 public interface PerFileMappingsEx<T> extends PerFileMappings<T> {

  @NotNull
+  @Unmodifiable
  Map<VirtualFile, T> getMappings();

  void setMappings(@NotNull Map<VirtualFile, T> mappings);
@@ -65,6 +65,7 @@ public abstract class FileReferenceHelper {
   *
   * @return roots, which could be used as the start resolution context.
   */
+  @Unmodifiable
  public @NotNull Collection<PsiFileSystemItem> getRoots(@NotNull Module module, @NotNull VirtualFile hostFile) {
    return getRoots(module);
  }
@@ -400,6 +400,7 @@ public class FileReferenceSet implements FileReferenceSetParameters {
  /**
   * Finds file target contexts, locations where users can create a file. Includes only local file directory items.
   */
+  @Unmodifiable
  public Collection<FileTargetContext> getTargetContexts() {
    PsiFile file = getContainingFile();
    if (file == null) return emptyList();
@@ -462,6 +463,7 @@ public class FileReferenceSet implements FileReferenceSetParameters {
    return null;
  }

+  @Unmodifiable
  private @NotNull Collection<FileTargetContext> getTargetContextByFile(@NotNull PsiFile file) {
    boolean absolutePathReference = isAbsolutePathReference();

@@ -589,6 +591,7 @@ public class FileReferenceSet implements FileReferenceSetParameters {
    return new ArrayList<>(result);
  }

+  @Unmodifiable
  protected @NotNull Collection<PsiFileSystemItem> toFileSystemItems(VirtualFile... files) {
    return toFileSystemItems(Arrays.asList(files));
  }
@@ -289,6 +289,7 @@ class DocumentWindowImpl extends UserDataHolderBase implements Disposable, Docum
  }

  @Override
+  @Unmodifiable
  public @NotNull Collection<@NotNull StringOperation> prepareReplaceString(int startOffset, int endOffset, @NotNull CharSequence s) {
    if (isOneLine()) {
      s = StringUtil.replace(s.toString(), "\n", "");
@@ -30,10 +30,7 @@ import com.intellij.util.ObjectUtils;
 import com.intellij.util.Processor;
 import com.intellij.util.SmartList;
 import com.intellij.util.containers.ContainerUtil;
-import org.jetbrains.annotations.ApiStatus;
-import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
-import org.jetbrains.annotations.TestOnly;
+import org.jetbrains.annotations.*;

 import java.util.*;

@@ -367,6 +364,7 @@ public final class InjectedLanguageManagerImpl extends InjectedLanguageManager i
  }

  @Override
+  @Unmodifiable
  public @NotNull List<DocumentWindow> getCachedInjectedDocumentsInRange(@NotNull PsiFile hostPsiFile, @NotNull TextRange range) {
    return InjectedLanguageUtilBase.getCachedInjectedDocumentsInRange(hostPsiFile, range);
  }
@@ -7,6 +7,7 @@ import com.intellij.openapi.util.TextRange;
 import com.intellij.util.text.StringOperation;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.Collection;

@@ -53,5 +54,6 @@ public interface DocumentWindow extends Document {
   * <p>
   * This method doesn't modify the host document.
   */
+  @Unmodifiable
  @NotNull Collection<@NotNull StringOperation> prepareReplaceString(int startOffset, int endOffset, @NotNull CharSequence s);
 }
@@ -13,10 +13,7 @@ import com.intellij.psi.FileViewProvider;
 import com.intellij.psi.PsiElement;
 import com.intellij.psi.PsiFile;
 import com.intellij.psi.PsiLanguageInjectionHost;
-import org.jetbrains.annotations.Contract;
-import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
-import org.jetbrains.annotations.TestOnly;
+import org.jetbrains.annotations.*;

 import java.util.List;

@@ -92,6 +89,7 @@ public abstract class InjectedLanguageManager {

  public abstract PsiFile getTopLevelFile(@NotNull PsiElement element);

+  @Unmodifiable
  public abstract @NotNull List<DocumentWindow> getCachedInjectedDocumentsInRange(@NotNull PsiFile hostPsiFile, @NotNull TextRange range);

  public abstract void enumerate(@NotNull PsiElement host, @NotNull PsiLanguageInjectionHost.InjectedPsiVisitor visitor);
@@ -8,6 +8,7 @@ import com.intellij.openapi.vfs.VirtualFile;
 import com.intellij.util.ArrayUtilRt;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;

 import javax.swing.*;
 import java.util.Arrays;
@@ -66,6 +67,7 @@ public class DelegatingGlobalSearchScope extends GlobalSearchScope {
  }

  @Override
+  @Unmodifiable
  public @NotNull Collection<UnloadedModuleDescription> getUnloadedModulesBelongingToScope() {
    return getDelegate().getUnloadedModulesBelongingToScope();
  }
@@ -7,6 +7,7 @@ import com.intellij.openapi.project.Project;
 import com.intellij.openapi.vfs.VirtualFile;
 import org.jetbrains.annotations.NonNls;
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.Collection;

@@ -41,6 +42,7 @@ class GlobalAndLocalUnionScope extends GlobalSearchScope {
  }

  @Override
+  @Unmodifiable
  public @NotNull Collection<UnloadedModuleDescription> getUnloadedModulesBelongingToScope() {
    return myMyGlobalScope.getUnloadedModulesBelongingToScope();
  }
@@ -72,6 +72,7 @@ public abstract class GlobalSearchScope extends SearchScope implements ProjectAw
   * Returns descriptions of unloaded modules whose content might be included in this scope if they had been loaded. Actually, search in
   * unloaded modules isn't performed, so this method is used to determine whether a warning about possible missing results should be shown.
   */
+  @Unmodifiable
  public @NotNull Collection<UnloadedModuleDescription> getUnloadedModulesBelongingToScope() {
    return Collections.emptySet();
  }
@@ -11,6 +11,7 @@ import com.intellij.util.containers.ContainerUtil;
 import org.jetbrains.annotations.NonNls;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.Arrays;
 import java.util.Collection;
@@ -75,6 +76,7 @@ final class IntersectionScope extends GlobalSearchScope implements VirtualFileEn
  }

  @Override
+  @Unmodifiable
  public @NotNull Collection<UnloadedModuleDescription> getUnloadedModulesBelongingToScope() {
    return ContainerUtil.intersection(myScope1.getUnloadedModulesBelongingToScope(), myScope2.getUnloadedModulesBelongingToScope());
  }
@@ -888,6 +888,7 @@ public class PsiTreeUtil {

  @SafeVarargs
  @Contract(pure = true)
+  @Unmodifiable
  public static @NotNull <T extends PsiElement> Collection<T> collectElementsOfType(@Nullable PsiElement element,
                                                                                    @NotNull Class<T> @NotNull ... classes) {
    return findChildrenOfAnyType(element, false, classes);
@@ -11,6 +11,7 @@ import com.intellij.util.containers.JBIterable;
 import com.intellij.util.io.URLUtil;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;

 import java.io.File;
 import java.util.*;
@@ -148,6 +149,7 @@ public final class PathsList  {
  /**
   * @return {@link VirtualFile}s on local file system (returns jars as files).
   */
+  @Unmodifiable
  public List<VirtualFile> getVirtualFiles() {
    return JBIterable.from(getPathList()).filterMap(PATH_TO_LOCAL_VFILE).toList();
  }
@@ -155,6 +157,7 @@ public final class PathsList  {
  /**
   * @return The same as {@link #getVirtualFiles()} but returns jars as {@code JarFileSystem} roots.
   */
+  @Unmodifiable
  public List<VirtualFile> getRootDirs() {
    return JBIterable.from(getPathList()).filterMap(PATH_TO_DIR).toList();
  }
@@ -6,6 +6,7 @@ import com.intellij.openapi.progress.ProgressIndicator;
 import com.intellij.util.Chunk;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.Collection;
 import java.util.List;
@@ -17,6 +18,7 @@ public abstract class GraphAlgorithms {
    return ApplicationManager.getApplication().getService(GraphAlgorithms.class);
  }

+  @Unmodifiable
  public abstract <Node> @NotNull Collection<Node> findNodesWhichBelongToAnyPathBetweenTwoNodes(
    @NotNull Graph<Node> graph,
    @NotNull Node start,
@@ -34,6 +34,7 @@ public class ObjectStubTree<T extends Stub> {
    return myRoot;
  }

+  @Unmodifiable
  public @NotNull List<T> getPlainList() {
    return myPlainList;
  }
@@ -59,6 +60,7 @@ public class ObjectStubTree<T extends Stub> {
    return sink.getResult();
  }

+  @Unmodifiable
  protected @NotNull List<T> enumerateStubs(@NotNull Stub root) {
    List<T> result = new ArrayList<>();
    //noinspection rawtypes,unchecked
@@ -24,6 +24,7 @@ public class StubTree extends ObjectStubTree<StubElement<?>> {
  }

  @Override
+  @Unmodifiable
  protected @NotNull List<StubElement<?>> enumerateStubs(@NotNull Stub root) {
    return ((StubBase<?>)root).myStubList.finalizeLoadingStage().toPlainList();
  }
@@ -8,6 +8,7 @@ import com.intellij.util.graph.*;
 import org.jetbrains.annotations.ApiStatus;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.Unmodifiable;

 import java.util.*;
 import java.util.function.Consumer;
@@ -16,6 +17,7 @@ import java.util.function.Consumer;
 public final class GraphAlgorithmsImpl extends GraphAlgorithms {

  @Override
+  @Unmodifiable
  public @NotNull <Node> Collection<Node> findNodesWhichBelongToAnyPathBetweenTwoNodes(
    @NotNull Graph<Node> graph,
    @NotNull Node start,
@@ -75,6 +75,7 @@ public final class DvcsUtil {
  };

  @NotNull
+  @Unmodifiable
  public static List<VirtualFile> sortVirtualFilesByPresentation(@NotNull Collection<? extends VirtualFile> virtualFiles) {
    return ContainerUtil.sorted(virtualFiles, VIRTUAL_FILE_PRESENTATION_COMPARATOR);
  }
@@ -42,6 +42,7 @@ public abstract class AbstractTreeNode<T> extends PresentableNodeDescriptor<Abst
    myNodeWrapper = setInternalValue(value);
  }

+  @Unmodifiable
  public abstract @NotNull Collection<? extends AbstractTreeNode<?>> getChildren();

  protected boolean hasProblemFileBeneath() {
--- a/Show More
+++ b/Show More