diff --git a/json/src/com/jetbrains/jsonSchema/impl/JsonSchemaDocumentationProvider.java b/json/src/com/jetbrains/jsonSchema/impl/JsonSchemaDocumentationProvider.java
index 562c6499f820..a2c746f8b40a 100644
--- a/json/src/com/jetbrains/jsonSchema/impl/JsonSchemaDocumentationProvider.java
+++ b/json/src/com/jetbrains/jsonSchema/impl/JsonSchemaDocumentationProvider.java
@@ -31,12 +31,6 @@ public class JsonSchemaDocumentationProvider implements DocumentationProvider {
     return findSchemaAndGenerateDoc(element, originalElement, true, null);
   }
 
-  @Nullable
-  @Override
-  public List<String> getUrlFor(PsiElement element, PsiElement originalElement) {
-    return null;
-  }
-
   @Nullable
   @Override
   public String generateDoc(PsiElement element, @Nullable PsiElement originalElement) {
@@ -213,12 +207,6 @@ public class JsonSchemaDocumentationProvider implements DocumentationProvider {
     return null;
   }
 
-  @Nullable
-  @Override
-  public PsiElement getDocumentationElementForLink(PsiManager psiManager, String link, PsiElement context) {
-    return null;
-  }
-
   private static class FakeDocElement extends FakePsiElement {
     private final PsiElement myContextElement;
     private final String myAltName;
diff --git a/platform/lang-api/src/com/intellij/lang/documentation/DocumentationProvider.java b/platform/lang-api/src/com/intellij/lang/documentation/DocumentationProvider.java
index df5c02576a55..4f621089c881 100644
--- a/platform/lang-api/src/com/intellij/lang/documentation/DocumentationProvider.java
+++ b/platform/lang-api/src/com/intellij/lang/documentation/DocumentationProvider.java
@@ -1,19 +1,4 @@
-/*
- * Copyright 2000-2015 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
+// Copyright 2000-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 package com.intellij.lang.documentation;
 
 import com.intellij.codeInsight.documentation.DocumentationManagerProtocol;
@@ -47,24 +32,29 @@ public interface DocumentationProvider {
    *                        a method reference, this will be the method to which the reference is resolved).
    * @param originalElement the element under the mouse cursor
    * @return the documentation to show, or null if the provider can't provide any documentation for this element. Documentation can contain
-   *         HTML markup. If HTML special characters need to be shown in popup, they should be properly escaped.
+   * HTML markup. If HTML special characters need to be shown in popup, they should be properly escaped.
    */
   @Nullable
-  String getQuickNavigateInfo(PsiElement element, PsiElement originalElement);
+  default String getQuickNavigateInfo(PsiElement element, PsiElement originalElement) {
+    return null;
+  }
 
   /**
    * Returns the list of possible URLs to show as external documentation for the specified element.
+   *
    * @param element         the element for which the documentation is requested (for example, if the mouse is over
    *                        a method reference, this will be the method to which the reference is resolved).
    * @param originalElement the element under the mouse cursor
    * @return the list of URLs to open in the browser or to use for showing documentation internally ({@link ExternalDocumentationProvider}).
-   *         If the list contains a single URL, it will be opened.
-   *         If the list contains multiple URLs, the user will be prompted to choose one of them.
-   *         For {@link ExternalDocumentationProvider}, first URL, yielding non-empty result in
-   *         {@link ExternalDocumentationProvider#fetchExternalDocumentation(Project, PsiElement, List)} will be used.
+   * If the list contains a single URL, it will be opened.
+   * If the list contains multiple URLs, the user will be prompted to choose one of them.
+   * For {@link ExternalDocumentationProvider}, first URL, yielding non-empty result in
+   * {@link ExternalDocumentationProvider#fetchExternalDocumentation(Project, PsiElement, List)} will be used.
    */
   @Nullable
-  List<String> getUrlFor(PsiElement element, PsiElement originalElement);
+  default List<String> getUrlFor(PsiElement element, PsiElement originalElement) {
+    return null;
+  }
 
   /**
    * Callback for asking the doc provider for the complete documentation.
@@ -85,14 +75,18 @@ public interface DocumentationProvider {
    * @param element         the element for which the documentation is requested (for example, if the mouse is over
    *                        a method reference, this will be the method to which the reference is resolved).
    * @param originalElement the element under the mouse cursor
-   * @return                target element's documentation, or {@code null} if provider is unable to generate documentation
-   *                        for the given element
+   * @return target element's documentation, or {@code null} if provider is unable to generate documentation
+   * for the given element
    */
   @Nullable
-  String generateDoc(PsiElement element, @Nullable PsiElement originalElement);
+  default String generateDoc(PsiElement element, @Nullable PsiElement originalElement) {
+    return null;
+  }
 
   @Nullable
-  PsiElement getDocumentationElementForLookupItem(PsiManager psiManager, Object object, PsiElement element);
+  default PsiElement getDocumentationElementForLookupItem(PsiManager psiManager, Object object, PsiElement element) {
+    return null;
+  }
 
   /**
    * Returns the target element for a link in a documentation comment. The link needs to use the
@@ -105,5 +99,7 @@ public interface DocumentationProvider {
    * @see DocumentationManagerUtil#createHyperlink(StringBuilder, String, String, boolean)
    */
   @Nullable
-  PsiElement getDocumentationElementForLink(PsiManager psiManager, String link, PsiElement context);
+  default PsiElement getDocumentationElementForLink(PsiManager psiManager, String link, PsiElement context) {
+    return null;
+  }
 }
diff --git a/platform/lang-api/src/com/intellij/lang/documentation/DocumentationProviderEx.java b/platform/lang-api/src/com/intellij/lang/documentation/DocumentationProviderEx.java
index 50dd1db2fa5d..99b46f54339e 100644
--- a/platform/lang-api/src/com/intellij/lang/documentation/DocumentationProviderEx.java
+++ b/platform/lang-api/src/com/intellij/lang/documentation/DocumentationProviderEx.java
@@ -1,59 +1,18 @@
-/*
- * Copyright 2000-2012 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
+// Copyright 2000-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 package com.intellij.lang.documentation;
 
 import com.intellij.openapi.editor.Editor;
 import com.intellij.psi.PsiElement;
 import com.intellij.psi.PsiFile;
-import com.intellij.psi.PsiManager;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
 import java.awt.*;
-import java.util.List;
 
 /**
  * @author peter
  */
 public class DocumentationProviderEx implements DocumentationProvider {
-  @Nullable
-  @Override
-  public String getQuickNavigateInfo(PsiElement element, PsiElement originalElement) {
-    return null; 
-  }
-
-  @Override
-  public List<String> getUrlFor(PsiElement element, PsiElement originalElement) {
-    return null; 
-  }
-
-  @Override
-  public String generateDoc(PsiElement element, @Nullable PsiElement originalElement) {
-    return null; 
-  }
-
-  @Override
-  public PsiElement getDocumentationElementForLookupItem(PsiManager psiManager, Object object, PsiElement element) {
-    return null; 
-  }
-
-  @Override
-  public PsiElement getDocumentationElementForLink(PsiManager psiManager, String link, PsiElement context) {
-    return null; 
-  }
 
   /**
    * @param contextElement the leaf PSI element in {@code file} at the editor's caret offset.
diff --git a/plugins/ant/src/com/intellij/lang/ant/doc/AntDomDocumentationProvider.java b/plugins/ant/src/com/intellij/lang/ant/doc/AntDomDocumentationProvider.java
index f0b0493dc541..8fd57e29c152 100644
--- a/plugins/ant/src/com/intellij/lang/ant/doc/AntDomDocumentationProvider.java
+++ b/plugins/ant/src/com/intellij/lang/ant/doc/AntDomDocumentationProvider.java
@@ -1,18 +1,4 @@
-/*
- * Copyright 2000-2010 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
+// Copyright 2000-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 package com.intellij.lang.ant.doc;
 
 import com.intellij.lang.ant.AntFilesProvider;
@@ -29,7 +15,6 @@ import com.intellij.pom.PomTarget;
 import com.intellij.pom.PomTargetPsiElement;
 import com.intellij.psi.PsiElement;
 import com.intellij.psi.PsiFile;
-import com.intellij.psi.PsiManager;
 import com.intellij.psi.util.PsiTreeUtil;
 import com.intellij.psi.xml.XmlElement;
 import com.intellij.psi.xml.XmlTag;
@@ -251,14 +236,4 @@ public class AntDomDocumentationProvider implements DocumentationProvider {
     }
     return Collections.singletonList(helpFile.getUrl());
   }
-
-  @Override
-  public PsiElement getDocumentationElementForLookupItem(PsiManager psiManager, Object object, PsiElement element) {
-    return null;
-  }
-
-  @Override
-  public PsiElement getDocumentationElementForLink(PsiManager psiManager, String link, PsiElement context) {
-    return null;
-  }
 }
diff --git a/plugins/gradle/java/src/documentation/GradleDocumentationProvider.java b/plugins/gradle/java/src/documentation/GradleDocumentationProvider.java
index 480c1bedfe5a..d841c744f894 100644
--- a/plugins/gradle/java/src/documentation/GradleDocumentationProvider.java
+++ b/plugins/gradle/java/src/documentation/GradleDocumentationProvider.java
@@ -1,18 +1,4 @@
-/*
- * Copyright 2000-2013 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
+// Copyright 2000-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 package org.jetbrains.plugins.gradle.documentation;
 
 import com.intellij.codeInsight.javadoc.JavaDocUtil;
@@ -34,8 +20,6 @@ import org.jetbrains.plugins.groovy.lang.psi.api.statements.expressions.GrCall;
 import org.jetbrains.plugins.groovy.lang.psi.api.statements.expressions.literals.GrLiteral;
 import org.jetbrains.plugins.groovy.lang.psi.impl.synthetic.GrLightVariable;
 
-import java.util.List;
-
 /**
  * @author Vladislav.Soroka
  */
@@ -56,12 +40,6 @@ public class GradleDocumentationProvider implements DocumentationProvider {
     return null;
   }
 
-  @Nullable
-  @Override
-  public List<String> getUrlFor(PsiElement element, PsiElement originalElement) {
-    return null;
-  }
-
   @Nullable
   @Override
   public String generateDoc(PsiElement element, PsiElement originalElement) {
diff --git a/plugins/maven/src/main/java/org/jetbrains/idea/maven/dom/MavenModelDocumentationProvider.java b/plugins/maven/src/main/java/org/jetbrains/idea/maven/dom/MavenModelDocumentationProvider.java
index 33e658cb7c7c..31cef41829c4 100644
--- a/plugins/maven/src/main/java/org/jetbrains/idea/maven/dom/MavenModelDocumentationProvider.java
+++ b/plugins/maven/src/main/java/org/jetbrains/idea/maven/dom/MavenModelDocumentationProvider.java
@@ -1,24 +1,13 @@
-/*
- * Copyright 2000-2009 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
+// Copyright 2000-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 package org.jetbrains.idea.maven.dom;
 
 import com.intellij.lang.documentation.DocumentationProvider;
 import com.intellij.lang.findUsages.DescriptiveNameUtil;
 import com.intellij.openapi.util.text.StringUtil;
-import com.intellij.psi.*;
+import com.intellij.psi.ElementDescriptionLocation;
+import com.intellij.psi.ElementDescriptionProvider;
+import com.intellij.psi.PsiElement;
+import com.intellij.psi.PsiFile;
 import com.intellij.psi.impl.FakePsiElement;
 import com.intellij.psi.util.PsiTreeUtil;
 import com.intellij.psi.xml.XmlTag;
@@ -55,16 +44,6 @@ public class MavenModelDocumentationProvider implements DocumentationProvider, E
     return getDoc(element, true);
   }
 
-  @Override
-  public PsiElement getDocumentationElementForLookupItem(PsiManager psiManager, Object object, PsiElement element) {
-    return null;
-  }
-
-  @Override
-  public PsiElement getDocumentationElementForLink(PsiManager psiManager, String link, PsiElement context) {
-    return null;
-  }
-
   @Nullable
   private static String getDoc(PsiElement element, boolean html) {
     return getMavenElementDescription(element, DescKind.TYPE_NAME_VALUE, html);
diff --git a/plugins/maven/src/main/java/org/jetbrains/idea/maven/dom/MavenPluginModelDocumentationProvider.java b/plugins/maven/src/main/java/org/jetbrains/idea/maven/dom/MavenPluginModelDocumentationProvider.java
index 520464cab9c2..f2c59547c9f8 100644
--- a/plugins/maven/src/main/java/org/jetbrains/idea/maven/dom/MavenPluginModelDocumentationProvider.java
+++ b/plugins/maven/src/main/java/org/jetbrains/idea/maven/dom/MavenPluginModelDocumentationProvider.java
@@ -1,25 +1,8 @@
-/*
- * Copyright 2000-2009 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
+// Copyright 2000-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 package org.jetbrains.idea.maven.dom;
 
 import com.intellij.lang.documentation.DocumentationProvider;
 import com.intellij.psi.PsiElement;
-import com.intellij.psi.PsiManager;
-
-import java.util.List;
 
 public class MavenPluginModelDocumentationProvider implements DocumentationProvider {
   @Override
@@ -27,26 +10,11 @@ public class MavenPluginModelDocumentationProvider implements DocumentationProvi
     return getDocForMavenPluginParameter(element, false);
   }
 
-  @Override
-  public List<String> getUrlFor(PsiElement element, PsiElement originalElement) {
-    return null;
-  }
-
   @Override
   public String generateDoc(PsiElement element, PsiElement originalElement) {
     return getDocForMavenPluginParameter(element, true);
   }
 
-  @Override
-  public PsiElement getDocumentationElementForLookupItem(PsiManager psiManager, Object object, PsiElement element) {
-    return null;
-  }
-
-  @Override
-  public PsiElement getDocumentationElementForLink(PsiManager psiManager, String link, PsiElement context) {
-    return null;
-  }
-
   private String getDocForMavenPluginParameter(PsiElement element, boolean html) {
     MavenPluginConfigurationDomExtender.ParameterData p = element.getUserData(MavenPluginConfigurationDomExtender.PLUGIN_PARAMETER_KEY);
     if (p == null) return null;
diff --git a/plugins/maven/src/main/java/org/jetbrains/idea/maven/dom/MavenPomXmlDocumentationProvider.java b/plugins/maven/src/main/java/org/jetbrains/idea/maven/dom/MavenPomXmlDocumentationProvider.java
index a1e73cc90aee..ef151a2c785e 100644
--- a/plugins/maven/src/main/java/org/jetbrains/idea/maven/dom/MavenPomXmlDocumentationProvider.java
+++ b/plugins/maven/src/main/java/org/jetbrains/idea/maven/dom/MavenPomXmlDocumentationProvider.java
@@ -1,18 +1,4 @@
-/*
- * Copyright 2000-2012 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
+// Copyright 2000-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 package org.jetbrains.idea.maven.dom;
 
 import com.intellij.lang.documentation.DocumentationProvider;
@@ -80,10 +66,4 @@ public class MavenPomXmlDocumentationProvider implements DocumentationProvider {
 
     return myDelegate.getDocumentationElementForLookupItem(psiManager, object, element);
   }
-
-  @Nullable
-  @Override
-  public PsiElement getDocumentationElementForLink(PsiManager psiManager, String link, PsiElement context) {
-    return null;
-  }
 }
diff --git a/plugins/xpath/xpath-lang/src/org/intellij/lang/xpath/xslt/impl/XsltDocumentationProvider.java b/plugins/xpath/xpath-lang/src/org/intellij/lang/xpath/xslt/impl/XsltDocumentationProvider.java
index 4f60f592f52e..6dd5d17776d6 100644
--- a/plugins/xpath/xpath-lang/src/org/intellij/lang/xpath/xslt/impl/XsltDocumentationProvider.java
+++ b/plugins/xpath/xpath-lang/src/org/intellij/lang/xpath/xslt/impl/XsltDocumentationProvider.java
@@ -230,12 +230,6 @@ public class XsltDocumentationProvider implements DocumentationProvider {
         return null;
     }
 
-    @Override
-    @Nullable
-    public String getQuickNavigateInfo(PsiElement element, PsiElement originalElement) {
-        return null;
-    }
-
     static class DocElement extends LightElement implements PsiNamedElement {
         private final PsiElement myElement;
         private final String myCategory;
diff --git a/plugins/yaml/src/org/jetbrains/yaml/meta/impl/YamlDocumentationProviderBase.java b/plugins/yaml/src/org/jetbrains/yaml/meta/impl/YamlDocumentationProviderBase.java
index b5a1c2ce514c..dfa5d5ba3026 100644
--- a/plugins/yaml/src/org/jetbrains/yaml/meta/impl/YamlDocumentationProviderBase.java
+++ b/plugins/yaml/src/org/jetbrains/yaml/meta/impl/YamlDocumentationProviderBase.java
@@ -1,6 +1,4 @@
-/*
- * Copyright 2000-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
- */
+// Copyright 2000-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 package org.jetbrains.yaml.meta.impl;
 
 import com.intellij.lang.documentation.AbstractDocumentationProvider;
@@ -28,11 +26,6 @@ import java.util.Objects;
 
 @ApiStatus.Experimental
 public abstract class YamlDocumentationProviderBase extends AbstractDocumentationProvider {
-  @Override
-  @Nullable
-  public String getQuickNavigateInfo(PsiElement element, PsiElement originalElement) {
-    return null;
-  }
 
   @Override
   public String generateDoc(PsiElement element, @Nullable PsiElement originalElement) {
diff --git a/plugins/yaml/src/org/jetbrains/yaml/schema/YamlJsonSchemaDocumentationProvider.java b/plugins/yaml/src/org/jetbrains/yaml/schema/YamlJsonSchemaDocumentationProvider.java
index a4a7775c0af6..b2a28d3cb5e4 100644
--- a/plugins/yaml/src/org/jetbrains/yaml/schema/YamlJsonSchemaDocumentationProvider.java
+++ b/plugins/yaml/src/org/jetbrains/yaml/schema/YamlJsonSchemaDocumentationProvider.java
@@ -1,19 +1,16 @@
-// Copyright 2000-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
+// Copyright 2000-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 package org.jetbrains.yaml.schema;
 
 import com.intellij.lang.documentation.DocumentationProviderEx;
 import com.intellij.openapi.editor.Editor;
 import com.intellij.psi.PsiElement;
 import com.intellij.psi.PsiFile;
-import com.intellij.psi.PsiManager;
 import com.jetbrains.jsonSchema.ide.JsonSchemaService;
 import com.jetbrains.jsonSchema.impl.JsonSchemaDocumentationProvider;
 import com.jetbrains.jsonSchema.impl.JsonSchemaObject;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
-import java.util.List;
-
 public class YamlJsonSchemaDocumentationProvider extends DocumentationProviderEx {
   @Nullable
   @Override
@@ -21,12 +18,6 @@ public class YamlJsonSchemaDocumentationProvider extends DocumentationProviderEx
     return findSchemaAndGenerateDoc(element, true);
   }
 
-  @Nullable
-  @Override
-  public List<String> getUrlFor(PsiElement element, PsiElement originalElement) {
-    return null;
-  }
-
   @Nullable
   @Override
   public String generateDoc(PsiElement element, @Nullable PsiElement originalElement) {
@@ -43,18 +34,6 @@ public class YamlJsonSchemaDocumentationProvider extends DocumentationProviderEx
     return JsonSchemaDocumentationProvider.generateDoc(element, schemaObject, preferShort, null);
   }
 
-  @Nullable
-  @Override
-  public PsiElement getDocumentationElementForLookupItem(PsiManager psiManager, Object object, PsiElement element) {
-    return null;
-  }
-
-  @Nullable
-  @Override
-  public PsiElement getDocumentationElementForLink(PsiManager psiManager, String link, PsiElement context) {
-    return null;
-  }
-
   @Nullable
   @Override
   public PsiElement getCustomDocumentationElement(@NotNull Editor editor,
diff --git a/xml/dom-impl/src/com/intellij/util/xml/DomDocumentationProvider.java b/xml/dom-impl/src/com/intellij/util/xml/DomDocumentationProvider.java
index 086141f855b3..9c5be9a5d2c6 100644
--- a/xml/dom-impl/src/com/intellij/util/xml/DomDocumentationProvider.java
+++ b/xml/dom-impl/src/com/intellij/util/xml/DomDocumentationProvider.java
@@ -1,18 +1,4 @@
-/*
- * Copyright 2000-2014 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
+// Copyright 2000-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 package com.intellij.util.xml;
 
 import com.intellij.lang.documentation.DocumentationProvider;
@@ -20,25 +6,12 @@ import com.intellij.pom.PomTarget;
 import com.intellij.pom.PomTargetPsiElement;
 import com.intellij.psi.DelegatePsiTarget;
 import com.intellij.psi.PsiElement;
-import com.intellij.psi.PsiManager;
-
-import java.util.List;
 
 /**
  * @author Dmitry Avdeev
  */
 public class DomDocumentationProvider implements DocumentationProvider {
 
-  @Override
-  public String getQuickNavigateInfo(final PsiElement element, PsiElement originalElement) {
-    return null;
-  }
-
-  @Override
-  public List<String> getUrlFor(final PsiElement element, final PsiElement originalElement) {
-    return null;
-  }
-
   @Override
   public String generateDoc(PsiElement element, final PsiElement originalElement) {
     if (element instanceof PomTargetPsiElement) {
@@ -58,14 +31,4 @@ public class DomDocumentationProvider implements DocumentationProvider {
     }
     return ElementPresentationManager.getDocumentationForElement(domElement);
   }
-
-  @Override
-  public PsiElement getDocumentationElementForLookupItem(final PsiManager psiManager, final Object object, final PsiElement element) {
-    return null;
-  }
-
-  @Override
-  public PsiElement getDocumentationElementForLink(final PsiManager psiManager, final String link, final PsiElement context) {
-    return null;
-  }
 }
diff --git a/xml/impl/src/com/intellij/xml/util/documentation/XmlDocumentationProvider.java b/xml/impl/src/com/intellij/xml/util/documentation/XmlDocumentationProvider.java
index 80566d9ba549..41e588384007 100644
--- a/xml/impl/src/com/intellij/xml/util/documentation/XmlDocumentationProvider.java
+++ b/xml/impl/src/com/intellij/xml/util/documentation/XmlDocumentationProvider.java
@@ -1,18 +1,4 @@
-/*
- * Copyright 2000-2015 JetBrains s.r.o.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
+// Copyright 2000-2019 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license that can be found in the LICENSE file.
 package com.intellij.xml.util.documentation;
 
 import com.intellij.lang.Language;
@@ -461,11 +447,6 @@ public class XmlDocumentationProvider implements DocumentationProvider {
     return null;
   }
 
-  @Override
-  public PsiElement getDocumentationElementForLink(final PsiManager psiManager, String link, PsiElement context) {
-    return null;
-  }
-
   private static class MyPsiElementProcessor implements PsiElementProcessor {
     String result;
     String version;
diff --git a/xml/relaxng/src/org/intellij/plugins/relaxNG/RngDocumentationProvider.java b/xml/relaxng/src/org/intellij/plugins/relaxNG/RngDocumentationProvider.java
index 402dcf4c5447..a805286e9be1 100644
--- a/xml/relaxng/src/org/intellij/plugins/relaxNG/RngDocumentationProvider.java
+++ b/xml/relaxng/src/org/intellij/plugins/relaxNG/RngDocumentationProvider.java
@@ -13,13 +13,11 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-
 package org.intellij.plugins.relaxNG;
 
 import com.intellij.lang.documentation.DocumentationProvider;
 import com.intellij.openapi.diagnostic.Logger;
 import com.intellij.psi.PsiElement;
-import com.intellij.psi.PsiManager;
 import com.intellij.psi.util.PsiTreeUtil;
 import com.intellij.psi.xml.XmlAttribute;
 import com.intellij.psi.xml.XmlElement;
@@ -37,7 +35,6 @@ import org.jetbrains.annotations.Nullable;
 import org.kohsuke.rngom.digested.DElementPattern;
 
 import java.util.Collection;
-import java.util.List;
 
 public class RngDocumentationProvider implements DocumentationProvider {
   private static final Logger LOG = Logger.getInstance(RngDocumentationProvider.class);
@@ -130,29 +127,6 @@ public class RngDocumentationProvider implements DocumentationProvider {
     return null;
   }
 
-  @Override
-  @Nullable
-  public PsiElement getDocumentationElementForLink(PsiManager psiManager, String link, PsiElement context) {
-    return null;
-  }
-
-  @Override
-  @Nullable
-  public PsiElement getDocumentationElementForLookupItem(PsiManager psiManager, Object object, PsiElement element) {
-    return null;
-  }
-
-  @Override
-  @Nullable
-  public String getQuickNavigateInfo(PsiElement element, PsiElement originalElement) {
-    return null;
-  }
-
-  @Override
-  public List<String> getUrlFor(PsiElement element, PsiElement originalElement) {
-    return null;
-  }
-
   public int hashCode() {
     return 0;   // CompositeDocumentationProvider uses a HashSet that doesn't preserve order. We want to be the first one.
   }
diff --git a/xml/relaxng/src/org/intellij/plugins/relaxNG/compact/RngCompactLanguage.java b/xml/relaxng/src/org/intellij/plugins/relaxNG/compact/RngCompactLanguage.java
index aada6617f02e..64998e58ab4d 100644
--- a/xml/relaxng/src/org/intellij/plugins/relaxNG/compact/RngCompactLanguage.java
+++ b/xml/relaxng/src/org/intellij/plugins/relaxNG/compact/RngCompactLanguage.java
@@ -25,7 +25,10 @@ import com.intellij.lang.refactoring.NamesValidator;
 import com.intellij.openapi.fileTypes.SingleLazyInstanceSyntaxHighlighterFactory;
 import com.intellij.openapi.fileTypes.SyntaxHighlighter;
 import com.intellij.openapi.project.Project;
-import com.intellij.psi.*;
+import com.intellij.psi.PsiComment;
+import com.intellij.psi.PsiElement;
+import com.intellij.psi.PsiFile;
+import com.intellij.psi.PsiWhiteSpace;
 import com.intellij.psi.tree.IElementType;
 import org.intellij.plugins.relaxNG.compact.psi.RncDefine;
 import org.intellij.plugins.relaxNG.compact.psi.RncElement;
@@ -34,8 +37,6 @@ import org.intellij.plugins.relaxNG.compact.psi.util.RenameUtil;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
-import java.util.List;
-
 public class RngCompactLanguage extends Language {
   public static final String ID = "RELAX-NG";
 
@@ -116,16 +117,6 @@ public class RngCompactLanguage extends Language {
   }
 
   public static class MyDocumentationProvider implements DocumentationProvider {
-    @Override
-    @Nullable
-    public String getQuickNavigateInfo(PsiElement element, PsiElement originalElement) {
-      return null;
-    }
-
-    @Override
-    public List<String> getUrlFor(PsiElement element, PsiElement originalElement) {
-      return null;
-    }
 
     @Override
     @Nullable
@@ -151,18 +142,6 @@ public class RngCompactLanguage extends Language {
       }
       return null;
     }
-
-    @Override
-    @Nullable
-    public PsiElement getDocumentationElementForLookupItem(PsiManager psiManager, Object object, PsiElement element) {
-      return null;
-    }
-
-    @Override
-    @Nullable
-    public PsiElement getDocumentationElementForLink(PsiManager psiManager, String link, PsiElement context) {
-      return null;
-    }
   }
 
   public static class MySyntaxHighlighterFactory extends SingleLazyInstanceSyntaxHighlighterFactory {