code samples: apply "Plugin DevKit | Code | Extension class should be final and non-public"

code_samples/comparing_string_references_inspection/src/main/java/org/intellij/sdk/codeInspection/ComparingStringReferencesInspection.java

@@ -16,7 +16,7 @@ import org.jetbrains.annotations.NotNull;
  * Implements an inspection to detect when String references are compared using 'a==b' or 'a!=b'.
  * The quick fix converts these comparisons to 'a.equals(b) or '!a.equals(b)' respectively.
  */
-public class ComparingStringReferencesInspection extends AbstractBaseJavaLocalInspectionTool {
+final class ComparingStringReferencesInspection extends AbstractBaseJavaLocalInspectionTool {
 
   private final ReplaceWithEqualsQuickFix myQuickFix = new ReplaceWithEqualsQuickFix();
 

code_samples/conditional_operator_intention/src/main/java/org/intellij/sdk/intention/ConditionalOperatorConverter.java

@@ -17,7 +17,7 @@ import org.jetbrains.annotations.Nullable;
  * Implements an intention action to replace a ternary statement with if-then-else.
  */
 @NonNls
-public class ConditionalOperatorConverter extends PsiElementBaseIntentionAction implements IntentionAction {
+final class ConditionalOperatorConverter extends PsiElementBaseIntentionAction implements IntentionAction {
 
   /**
    * Checks whether this intention is available at the caret offset in file - the caret must sit just before a "?"

code_samples/editor_basics/src/main/java/org/intellij/sdk/editor/MyTypedHandler.java

@@ -1,4 +1,4 @@
-// Copyright 2000-2022 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+// Copyright 2000-2023 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 
 package org.intellij.sdk.editor;
 
@@ -15,7 +15,7 @@ import org.jetbrains.annotations.NotNull;
  * The execute method inserts a fixed string at Offset 0 of the document.
  * Document changes are made in the context of a write action.
  */
-class MyTypedHandler extends TypedHandlerDelegate {
+final class MyTypedHandler extends TypedHandlerDelegate {
 
   @NotNull
   @Override

code_samples/facet_basics/src/main/java/org/intellij/sdk/facet/DemoFacetType.java

@@ -1,4 +1,4 @@
-// Copyright 2000-2022 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+// Copyright 2000-2023 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 
 package org.intellij.sdk.facet;
 
@@ -18,7 +18,7 @@ import javax.swing.*;
  * Provides creation of {@link DemoFacet} and associated Configuration.
  * Allows application of this facet to all {@link ModuleType} instances.
  */
-public class DemoFacetType extends FacetType<DemoFacet, DemoFacetConfiguration> {
+final class DemoFacetType extends FacetType<DemoFacet, DemoFacetConfiguration> {
 
   public static final String FACET_ID = "DEMO_FACET_ID";
   public static final String FACET_NAME = "SDK Facet";

code_samples/framework_basics/src/main/java/org/intellij/sdk/framework/DemoFramework.java

@@ -1,4 +1,4 @@
-// Copyright 2000-2022 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+// Copyright 2000-2023 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 
 package org.intellij.sdk.framework;
 
@@ -15,11 +15,11 @@ import org.jetbrains.annotations.NotNull;
 
 import javax.swing.*;
 
-public class DemoFramework extends FrameworkTypeEx {
+final class DemoFramework extends FrameworkTypeEx {
 
   public static final String FRAMEWORK_ID = "org.intellij.sdk.framework.DemoFramework";
 
-  protected DemoFramework() {
+  DemoFramework() {
     super(FRAMEWORK_ID);
   }
 

code_samples/live_templates/src/main/java/org/intellij/sdk/liveTemplates/MarkdownContext.java

@@ -6,9 +6,9 @@ import com.intellij.codeInsight.template.TemplateActionContext;
 import com.intellij.codeInsight.template.TemplateContextType;
 import org.jetbrains.annotations.NotNull;
 
-public class MarkdownContext extends TemplateContextType {
+final class MarkdownContext extends TemplateContextType {
 
-  protected MarkdownContext() {
+  MarkdownContext() {
     super("Markdown");
   }
 

code_samples/live_templates/src/main/java/org/intellij/sdk/liveTemplates/TitleCaseMacro.java

@@ -1,4 +1,4 @@
-// Copyright 2000-2022 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+// Copyright 2000-2023 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 
 package org.intellij.sdk.liveTemplates;
 
@@ -7,7 +7,7 @@ import com.intellij.codeInsight.template.macro.MacroBase;
 import com.intellij.openapi.util.text.StringUtil;
 import org.jetbrains.annotations.NotNull;
 
-public class TitleCaseMacro extends MacroBase {
+final class TitleCaseMacro extends MacroBase {
 
   public TitleCaseMacro() {
     super("titleCase", "titleCase(String)");

code_samples/max_opened_projects/src/main/java/org/intellij/sdk/maxOpenProjects/ProjectOpenStartupActivity.java

@@ -11,7 +11,7 @@ import org.jetbrains.annotations.NotNull;
 /**
  * Invoked on opening a project.
  */
-public class ProjectOpenStartupActivity implements StartupActivity.DumbAware {
+final class ProjectOpenStartupActivity implements StartupActivity.DumbAware {
 
   @Override
   public void runActivity(@NotNull Project project) {

code_samples/module/src/main/java/org/intellij/sdk/module/DemoModuleType.java

@@ -1,4 +1,4 @@
-// Copyright 2000-2022 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+// Copyright 2000-2023 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 
 package org.intellij.sdk.module;
 
@@ -12,11 +12,11 @@ import org.jetbrains.annotations.NotNull;
 
 import javax.swing.*;
 
-public class DemoModuleType extends ModuleType<DemoModuleBuilder> {
+final class DemoModuleType extends ModuleType<DemoModuleBuilder> {
 
   private static final String ID = "DEMO_MODULE_TYPE";
 
-  public DemoModuleType() {
+  DemoModuleType() {
     super(ID);
   }
 

code_samples/project_view_pane/src/main/java/org/intellij/sdk/view/pane/ImagesProjectViewPane.java

@@ -13,11 +13,11 @@ import org.jetbrains.annotations.NotNull;
 
 import javax.swing.tree.DefaultTreeModel;
 
-public class ImagesProjectViewPane extends ProjectViewPane {
+final class ImagesProjectViewPane extends ProjectViewPane {
 
   public static final String ID = "IMAGES";
 
-  protected ImagesProjectViewPane(Project project) {
+  ImagesProjectViewPane(Project project) {
     super(project);
   }
 

code_samples/project_wizard/src/main/java/org/intellij/sdk/project/wizard/DemoModuleWizardStep.java

@@ -1,4 +1,4 @@
-// Copyright 2000-2022 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+// Copyright 2000-2023 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 
 package org.intellij.sdk.project.wizard;
 
@@ -12,7 +12,7 @@ import org.jetbrains.annotations.NotNull;
 
 import javax.swing.*;
 
-public class DemoModuleWizardStep extends ModuleBuilder {
+final class DemoModuleWizardStep extends ModuleBuilder {
 
   public void setupRootModel(@NotNull ModifiableRootModel modifiableRootModel) {
   }

code_samples/run_configuration/src/main/java/org/jetbrains/sdk/runConfiguration/DemoRunConfigurationType.java

@@ -5,11 +5,11 @@ import com.intellij.execution.configurations.ConfigurationTypeBase;
 import com.intellij.icons.AllIcons;
 import com.intellij.openapi.util.NotNullLazyValue;
 
-public class DemoRunConfigurationType extends ConfigurationTypeBase {
+final class DemoRunConfigurationType extends ConfigurationTypeBase {
 
   static final String ID = "DemoRunConfiguration";
 
-  protected DemoRunConfigurationType() {
+  DemoRunConfigurationType() {
     super(ID, "Demo", "Demo run configuration type",
         NotNullLazyValue.createValue(() -> AllIcons.Nodes.Console));
     addFactory(new DemoConfigurationFactory(this));

code_samples/settings/src/main/java/org/intellij/sdk/settings/AppSettingsConfigurable.java

@@ -10,7 +10,7 @@ import javax.swing.*;
 /**
  * Provides controller functionality for application settings.
  */
-public class AppSettingsConfigurable implements Configurable {
+final class AppSettingsConfigurable implements Configurable {
 
   private AppSettingsComponent mySettingsComponent;
 

code_samples/settings/src/main/java/org/intellij/sdk/settings/AppSettingsState.java

@@ -19,12 +19,12 @@ import org.jetbrains.annotations.Nullable;
     name = "org.intellij.sdk.settings.AppSettingsState",
     storages = @Storage("SdkSettingsPlugin.xml")
 )
-public class AppSettingsState implements PersistentStateComponent<AppSettingsState> {
+final class AppSettingsState implements PersistentStateComponent<AppSettingsState> {
 
   public String userId = "John Q. Public";
   public boolean ideaStatus = false;
 
-  public static AppSettingsState getInstance() {
+  static AppSettingsState getInstance() {
     return ApplicationManager.getApplication().getService(AppSettingsState.class);
   }
 

code_samples/simple_language_plugin/src/main/java/org/intellij/sdk/language/SimpleAnnotator.java

@@ -15,7 +15,7 @@ import org.jetbrains.annotations.NotNull;
 
 import java.util.List;
 
-public class SimpleAnnotator implements Annotator {
+final class SimpleAnnotator implements Annotator {
 
   // Define strings for the Simple language prefix - used for annotations, line markers, etc.
   public static final String SIMPLE_PREFIX_STR = "simple";

code_samples/simple_language_plugin/src/main/java/org/intellij/sdk/language/SimpleChooseByNameContributor.java

@@ -17,7 +17,7 @@ import org.jetbrains.annotations.Nullable;
 import java.util.List;
 import java.util.Objects;
 
-public class SimpleChooseByNameContributor implements ChooseByNameContributorEx {
+final class SimpleChooseByNameContributor implements ChooseByNameContributorEx {
 
   @Override
   public void processNames(@NotNull Processor<? super String> processor,

code_samples/simple_language_plugin/src/main/java/org/intellij/sdk/language/SimpleCodeStyleSettingsProvider.java

@@ -12,7 +12,7 @@ import com.intellij.psi.codeStyle.CustomCodeStyleSettings;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
-public class SimpleCodeStyleSettingsProvider extends CodeStyleSettingsProvider {
+final class SimpleCodeStyleSettingsProvider extends CodeStyleSettingsProvider {
 
   @Override
   public CustomCodeStyleSettings createCustomSettings(@NotNull CodeStyleSettings settings) {

code_samples/simple_language_plugin/src/main/java/org/intellij/sdk/language/SimpleColorSettingsPage.java

@@ -1,4 +1,4 @@
-// Copyright 2000-2022 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+// Copyright 2000-2023 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 
 package org.intellij.sdk.language;
 
@@ -13,7 +13,7 @@ import org.jetbrains.annotations.Nullable;
 import javax.swing.*;
 import java.util.Map;
 
-public class SimpleColorSettingsPage implements ColorSettingsPage {
+final class SimpleColorSettingsPage implements ColorSettingsPage {
 
   private static final AttributesDescriptor[] DESCRIPTORS = new AttributesDescriptor[]{
       new AttributesDescriptor("Key", SimpleSyntaxHighlighter.KEY),

code_samples/simple_language_plugin/src/main/java/org/intellij/sdk/language/SimpleCommenter.java

@@ -1,11 +1,11 @@
-// Copyright 2000-2022 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+// Copyright 2000-2023 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 
 package org.intellij.sdk.language;
 
 import com.intellij.lang.Commenter;
 import org.jetbrains.annotations.Nullable;
 
-public class SimpleCommenter implements Commenter {
+final class SimpleCommenter implements Commenter {
 
   @Nullable
   @Override

code_samples/simple_language_plugin/src/main/java/org/intellij/sdk/language/SimpleCompletionContributor.java

@@ -1,4 +1,4 @@
-// Copyright 2000-2022 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+// Copyright 2000-2023 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 
 package org.intellij.sdk.language;
 
@@ -9,9 +9,9 @@ import com.intellij.util.ProcessingContext;
 import org.intellij.sdk.language.psi.SimpleTypes;
 import org.jetbrains.annotations.NotNull;
 
-public class SimpleCompletionContributor extends CompletionContributor {
+final class SimpleCompletionContributor extends CompletionContributor {
 
-  public SimpleCompletionContributor() {
+  SimpleCompletionContributor() {
     extend(CompletionType.BASIC, PlatformPatterns.psiElement(SimpleTypes.VALUE),
         new CompletionProvider<>() {
           public void addCompletions(@NotNull CompletionParameters parameters,

code_samples/simple_language_plugin/src/main/java/org/intellij/sdk/language/SimpleDocumentationProvider.java

@@ -1,3 +1,4 @@
+// Copyright 2000-2023 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 package org.intellij.sdk.language;
 
 import com.intellij.lang.documentation.AbstractDocumentationProvider;
@@ -16,7 +17,7 @@ import java.util.List;
  *
  * @see <a href="https://plugins.jetbrains.com/docs/intellij/documentation.html">Documentation (IntelliJ Platform Docs)</a>
  */
-public class SimpleDocumentationProvider extends AbstractDocumentationProvider {
+final class SimpleDocumentationProvider extends AbstractDocumentationProvider {
 
   /**
    * For the Simple Language, we don't have online documentation. However, if your language provides

code_samples/simple_language_plugin/src/main/java/org/intellij/sdk/language/SimpleFileType.java

@@ -1,4 +1,4 @@
-// Copyright 2000-2022 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+// Copyright 2000-2023 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 
 package org.intellij.sdk.language;
 
@@ -8,7 +8,7 @@ import org.jetbrains.annotations.Nullable;
 
 import javax.swing.*;
 
-public class SimpleFileType extends LanguageFileType {
+public final class SimpleFileType extends LanguageFileType {
 
   public static final SimpleFileType INSTANCE = new SimpleFileType();
 

code_samples/simple_language_plugin/src/main/java/org/intellij/sdk/language/SimpleFindUsagesProvider.java

@@ -1,4 +1,4 @@
-// Copyright 2000-2022 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+// Copyright 2000-2023 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 
 package org.intellij.sdk.language;
 
@@ -13,7 +13,7 @@ import org.intellij.sdk.language.psi.SimpleTokenSets;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
-public class SimpleFindUsagesProvider implements FindUsagesProvider {
+final class SimpleFindUsagesProvider implements FindUsagesProvider {
 
   @Nullable
   @Override

code_samples/simple_language_plugin/src/main/java/org/intellij/sdk/language/SimpleFoldingBuilder.java

@@ -24,7 +24,7 @@ import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 
-public class SimpleFoldingBuilder extends FoldingBuilderEx implements DumbAware {
+final class SimpleFoldingBuilder extends FoldingBuilderEx implements DumbAware {
 
   @Override
   public FoldingDescriptor @NotNull [] buildFoldRegions(@NotNull PsiElement root, @NotNull Document document, boolean quick) {

code_samples/simple_language_plugin/src/main/java/org/intellij/sdk/language/SimpleFormattingModelBuilder.java

@@ -1,4 +1,4 @@
-// Copyright 2000-2022 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+// Copyright 2000-2023 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 
 package org.intellij.sdk.language;
 
@@ -7,7 +7,7 @@ import com.intellij.psi.codeStyle.CodeStyleSettings;
 import org.intellij.sdk.language.psi.SimpleTypes;
 import org.jetbrains.annotations.NotNull;
 
-public class SimpleFormattingModelBuilder implements FormattingModelBuilder {
+final class SimpleFormattingModelBuilder implements FormattingModelBuilder {
 
   private static SpacingBuilder createSpaceBuilder(CodeStyleSettings settings) {
     return new SpacingBuilder(settings, SimpleLanguage.INSTANCE)

code_samples/simple_language_plugin/src/main/java/org/intellij/sdk/language/SimpleLanguageCodeStyleSettingsProvider.java

@@ -1,4 +1,4 @@
-// Copyright 2000-2022 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+// Copyright 2000-2023 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 
 package org.intellij.sdk.language;
 
@@ -7,7 +7,7 @@ import com.intellij.psi.codeStyle.CodeStyleSettingsCustomizable;
 import com.intellij.psi.codeStyle.LanguageCodeStyleSettingsProvider;
 import org.jetbrains.annotations.NotNull;
 
-public class SimpleLanguageCodeStyleSettingsProvider extends LanguageCodeStyleSettingsProvider {
+final class SimpleLanguageCodeStyleSettingsProvider extends LanguageCodeStyleSettingsProvider {
 
   @NotNull
   @Override

code_samples/simple_language_plugin/src/main/java/org/intellij/sdk/language/SimpleLineMarkerProvider.java

@@ -1,4 +1,4 @@
-// Copyright 2000-2022 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+// Copyright 2000-2023 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 
 package org.intellij.sdk.language;
 
@@ -15,7 +15,7 @@ import org.jetbrains.annotations.NotNull;
 import java.util.Collection;
 import java.util.List;
 
-public class SimpleLineMarkerProvider extends RelatedItemLineMarkerProvider {
+final class SimpleLineMarkerProvider extends RelatedItemLineMarkerProvider {
 
   @Override
   protected void collectNavigationMarkers(@NotNull PsiElement element,

code_samples/simple_language_plugin/src/main/java/org/intellij/sdk/language/SimpleParserDefinition.java

@@ -1,4 +1,4 @@
-// Copyright 2000-2022 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+// Copyright 2000-2023 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 
 package org.intellij.sdk.language;
 
@@ -18,7 +18,7 @@ import org.intellij.sdk.language.psi.SimpleTokenSets;
 import org.intellij.sdk.language.psi.SimpleTypes;
 import org.jetbrains.annotations.NotNull;
 
-public class SimpleParserDefinition implements ParserDefinition {
+final class SimpleParserDefinition implements ParserDefinition {
 
   public static final IFileElementType FILE = new IFileElementType(SimpleLanguage.INSTANCE);
 

code_samples/simple_language_plugin/src/main/java/org/intellij/sdk/language/SimplePropertyIconProvider.java

@@ -10,7 +10,7 @@ import org.jetbrains.annotations.Nullable;
 
 import javax.swing.*;
 
-public class SimplePropertyIconProvider extends IconProvider {
+final class SimplePropertyIconProvider extends IconProvider {
 
   @Override
   public @Nullable Icon getIcon(@NotNull PsiElement element, int flags) {

code_samples/simple_language_plugin/src/main/java/org/intellij/sdk/language/SimpleRefactoringSupportProvider.java

@@ -1,4 +1,4 @@
-// Copyright 2000-2022 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+// Copyright 2000-2023 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 
 package org.intellij.sdk.language;
 
@@ -8,7 +8,7 @@ import org.intellij.sdk.language.psi.SimpleProperty;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
-public class SimpleRefactoringSupportProvider extends RefactoringSupportProvider {
+final class SimpleRefactoringSupportProvider extends RefactoringSupportProvider {
 
   @Override
   public boolean isMemberInplaceRenameAvailable(@NotNull PsiElement elementToRename, @Nullable PsiElement context) {

code_samples/simple_language_plugin/src/main/java/org/intellij/sdk/language/SimpleReferenceContributor.java

@@ -1,4 +1,4 @@
-// Copyright 2000-2022 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+// Copyright 2000-2023 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 
 package org.intellij.sdk.language;
 
@@ -11,7 +11,7 @@ import org.jetbrains.annotations.NotNull;
 import static org.intellij.sdk.language.SimpleAnnotator.SIMPLE_PREFIX_STR;
 import static org.intellij.sdk.language.SimpleAnnotator.SIMPLE_SEPARATOR_STR;
 
-public class SimpleReferenceContributor extends PsiReferenceContributor {
+final class SimpleReferenceContributor extends PsiReferenceContributor {
 
   @Override
   public void registerReferenceProviders(@NotNull PsiReferenceRegistrar registrar) {

code_samples/simple_language_plugin/src/main/java/org/intellij/sdk/language/SimpleSpellcheckingStrategy.java

@@ -1,4 +1,4 @@
-// Copyright 2000-2022 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+// Copyright 2000-2023 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
 
 package org.intellij.sdk.language;
 
@@ -16,7 +16,7 @@ import org.intellij.sdk.language.psi.SimpleProperty;
 import org.intellij.sdk.language.psi.SimpleTypes;
 import org.jetbrains.annotations.NotNull;
 
-public class SimpleSpellcheckingStrategy extends SpellcheckingStrategy {
+final class SimpleSpellcheckingStrategy extends SpellcheckingStrategy {
 
   @Override
   public @NotNull Tokenizer<?> getTokenizer(PsiElement element) {

code_samples/simple_language_plugin/src/main/java/org/intellij/sdk/language/SimpleStructureAwareNavbar.java

@@ -1,4 +1,4 @@
-// Copyright 2000-2022 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+// Copyright 2000-2023 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
 
 package org.intellij.sdk.language;
 
@@ -12,7 +12,7 @@ import org.jetbrains.annotations.Nullable;
 
 import javax.swing.Icon;
 
-public class SimpleStructureAwareNavbar extends StructureAwareNavBarModelExtension {
+final class SimpleStructureAwareNavbar extends StructureAwareNavBarModelExtension {
 
   @NotNull
   @Override

code_samples/simple_language_plugin/src/main/java/org/intellij/sdk/language/SimpleStructureViewFactory.java

@@ -1,4 +1,4 @@
-// Copyright 2000-2022 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+// Copyright 2000-2023 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
 
 package org.intellij.sdk.language;
 
@@ -11,7 +11,7 @@ import com.intellij.psi.PsiFile;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
-public class SimpleStructureViewFactory implements PsiStructureViewFactory {
+final class SimpleStructureViewFactory implements PsiStructureViewFactory {
 
   @Nullable
   @Override

code_samples/simple_language_plugin/src/main/java/org/intellij/sdk/language/SimpleSyntaxHighlighterFactory.java

@@ -1,4 +1,4 @@
-// Copyright 2000-2022 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+// Copyright 2000-2023 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 
 package org.intellij.sdk.language;
 
@@ -8,7 +8,7 @@ import com.intellij.openapi.project.Project;
 import com.intellij.openapi.vfs.VirtualFile;
 import org.jetbrains.annotations.NotNull;
 
-public class SimpleSyntaxHighlighterFactory extends SyntaxHighlighterFactory {
+final class SimpleSyntaxHighlighterFactory extends SyntaxHighlighterFactory {
 
   @NotNull
   @Override

code_samples/tool_window/src/main/java/org/intellij/sdk/toolWindow/CalendarToolWindowFactory.java

@@ -15,7 +15,7 @@ import java.awt.*;
 import java.util.Calendar;
 import java.util.Objects;
 
-public class CalendarToolWindowFactory implements ToolWindowFactory, DumbAware {
+final class CalendarToolWindowFactory implements ToolWindowFactory, DumbAware {
 
   @Override
   public void createToolWindowContent(@NotNull Project project, @NotNull ToolWindow toolWindow) {

code_samples/tree_structure_provider/src/main/java/org/intellij/sdk/treeStructureProvider/TextOnlyTreeStructureProvider.java

@@ -1,4 +1,4 @@
-// Copyright 2000-2022 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+// Copyright 2000-2023 JetBrains s.r.o. and other contributors. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 
 package org.intellij.sdk.treeStructureProvider;
 
@@ -13,7 +13,7 @@ import org.jetbrains.annotations.NotNull;
 import java.util.ArrayList;
 import java.util.Collection;
 
-public class TextOnlyTreeStructureProvider implements TreeStructureProvider {
+final class TextOnlyTreeStructureProvider implements TreeStructureProvider {
 
   @NotNull
   @Override