diff --git a/java/java-psi-impl/src/com/intellij/psi/impl/source/JavaFileElementType.java b/java/java-psi-impl/src/com/intellij/psi/impl/source/JavaFileElementType.java
index a67c1c281530..578f9052832f 100644
--- a/java/java-psi-impl/src/com/intellij/psi/impl/source/JavaFileElementType.java
+++ b/java/java-psi-impl/src/com/intellij/psi/impl/source/JavaFileElementType.java
@@ -77,7 +77,7 @@ public class JavaFileElementType extends ILightStubFileElementType<PsiJavaFileSt
   }
 
   @Override
-  public ASTNode parseContents(final ASTNode chameleon) {
+  public ASTNode parseContents(@NotNull final ASTNode chameleon) {
     final PsiBuilder builder = JavaParserUtil.createBuilder(chameleon);
     doParse(builder);
     return builder.getTreeBuilt().getFirstChildNode();
diff --git a/java/java-psi-impl/src/com/intellij/psi/impl/source/tree/JavaDocElementType.java b/java/java-psi-impl/src/com/intellij/psi/impl/source/tree/JavaDocElementType.java
index d3a07f30b4ee..8da543c8458b 100644
--- a/java/java-psi-impl/src/com/intellij/psi/impl/source/tree/JavaDocElementType.java
+++ b/java/java-psi-impl/src/com/intellij/psi/impl/source/tree/JavaDocElementType.java
@@ -81,7 +81,7 @@ public interface JavaDocElementType {
 
     @Nullable
     @Override
-    public ASTNode parseContents(final ASTNode chameleon) {
+    public ASTNode parseContents(@NotNull final ASTNode chameleon) {
       return JavaParserUtil.parseFragment(chameleon, myParser, false, LanguageLevel.JDK_1_3);
     }
   };
@@ -96,7 +96,7 @@ public interface JavaDocElementType {
 
     @Nullable
     @Override
-    public ASTNode parseContents(final ASTNode chameleon) {
+    public ASTNode parseContents(@NotNull final ASTNode chameleon) {
       return JavaParserUtil.parseFragment(chameleon, myParser, false, LanguageLevel.JDK_1_3);
     }
   };
@@ -116,7 +116,7 @@ public interface JavaDocElementType {
 
     @Nullable
     @Override
-    public ASTNode parseContents(final ASTNode chameleon) {
+    public ASTNode parseContents(@NotNull final ASTNode chameleon) {
       return JavaParserUtil.parseFragment(chameleon, myParser);
     }
 
diff --git a/java/java-psi-impl/src/com/intellij/psi/impl/source/tree/JavaElementType.java b/java/java-psi-impl/src/com/intellij/psi/impl/source/tree/JavaElementType.java
index 03e3aac370a6..d87d0ae797f6 100644
--- a/java/java-psi-impl/src/com/intellij/psi/impl/source/tree/JavaElementType.java
+++ b/java/java-psi-impl/src/com/intellij/psi/impl/source/tree/JavaElementType.java
@@ -164,7 +164,7 @@ public interface JavaElementType {
     }
 
     @Override
-    public ASTNode parseContents(final ASTNode chameleon) {
+    public ASTNode parseContents(@NotNull final ASTNode chameleon) {
       final PsiBuilder builder = JavaParserUtil.createBuilder(chameleon);
       JavaParser.INSTANCE.getStatementParser().parseCodeBlockDeep(builder, true);
       return builder.getTreeBuilt().getFirstChildNode();
@@ -195,7 +195,7 @@ public interface JavaElementType {
 
     @Nullable
     @Override
-    public ASTNode parseContents(final ASTNode chameleon) {
+    public ASTNode parseContents(@NotNull final ASTNode chameleon) {
       return JavaParserUtil.parseFragment(chameleon, myParser);
     }
   };
@@ -210,7 +210,7 @@ public interface JavaElementType {
 
     @Nullable
     @Override
-    public ASTNode parseContents(final ASTNode chameleon) {
+    public ASTNode parseContents(@NotNull final ASTNode chameleon) {
       return JavaParserUtil.parseFragment(chameleon, myParser);
     }
   };
@@ -225,7 +225,7 @@ public interface JavaElementType {
 
     @Nullable
     @Override
-    public ASTNode parseContents(final ASTNode chameleon) {
+    public ASTNode parseContents(@NotNull final ASTNode chameleon) {
       return JavaParserUtil.parseFragment(chameleon, myParser);
     }
   };
@@ -251,7 +251,7 @@ public interface JavaElementType {
 
     @Nullable
     @Override
-    public ASTNode parseContents(final ASTNode chameleon) {
+    public ASTNode parseContents(@NotNull final ASTNode chameleon) {
       return JavaParserUtil.parseFragment(chameleon, myParser);
     }
   }
@@ -269,7 +269,7 @@ public interface JavaElementType {
 
     @Nullable
     @Override
-    public ASTNode parseContents(final ASTNode chameleon) {
+    public ASTNode parseContents(@NotNull final ASTNode chameleon) {
       assert chameleon instanceof JavaDummyElement : chameleon;
       final JavaDummyElement dummyElement = (JavaDummyElement)chameleon;
       return JavaParserUtil.parseFragment(chameleon, dummyElement.getParser(), dummyElement.consumeAll(), dummyElement.getLanguageLevel());
diff --git a/java/java-tests/testSrc/com/intellij/java/parser/JavaParsingTestCase.java b/java/java-tests/testSrc/com/intellij/java/parser/JavaParsingTestCase.java
index dc40b89c5af3..05e74ba89c55 100644
--- a/java/java-tests/testSrc/com/intellij/java/parser/JavaParsingTestCase.java
+++ b/java/java-tests/testSrc/com/intellij/java/parser/JavaParsingTestCase.java
@@ -112,7 +112,7 @@ public abstract class JavaParsingTestCase extends ParsingTestCase {
     }
 
     @Override
-    public ASTNode parseContents(ASTNode chameleon) {
+    public ASTNode parseContents(@NotNull ASTNode chameleon) {
       PsiBuilder builder = createBuilder(chameleon);
 
       PsiBuilder.Marker root = builder.mark();
diff --git a/platform/core-api/src/com/intellij/psi/tree/IFileElementType.java b/platform/core-api/src/com/intellij/psi/tree/IFileElementType.java
index 565ae3447042..af5f788cf723 100644
--- a/platform/core-api/src/com/intellij/psi/tree/IFileElementType.java
+++ b/platform/core-api/src/com/intellij/psi/tree/IFileElementType.java
@@ -43,7 +43,7 @@ public class IFileElementType extends ILazyParseableElementType {
 
   @Nullable
   @Override
-  public ASTNode parseContents(final ASTNode chameleon) {
+  public ASTNode parseContents(@NotNull final ASTNode chameleon) {
     final PsiElement psi = chameleon.getPsi();
     assert psi != null : "Bad chameleon: " + chameleon;
     return doParseContents(chameleon, psi);
diff --git a/platform/core-api/src/com/intellij/psi/tree/ILazyParseableElementType.java b/platform/core-api/src/com/intellij/psi/tree/ILazyParseableElementType.java
index 86013e84ff36..87bb26e24ece 100644
--- a/platform/core-api/src/com/intellij/psi/tree/ILazyParseableElementType.java
+++ b/platform/core-api/src/com/intellij/psi/tree/ILazyParseableElementType.java
@@ -74,7 +74,7 @@ public class ILazyParseableElementType extends IElementType implements ILazyPars
    * @param chameleon the node to parse.
    * @return the parsed contents of the node.
    */
-  public ASTNode parseContents(ASTNode chameleon) {
+  public ASTNode parseContents(@NotNull ASTNode chameleon) {
     PsiElement parentElement = chameleon.getTreeParent().getPsi();
     assert parentElement != null : "parent psi is null: " + chameleon;
     return doParseContents(chameleon, parentElement);
diff --git a/platform/core-api/src/com/intellij/psi/tree/ILazyParseableElementTypeBase.java b/platform/core-api/src/com/intellij/psi/tree/ILazyParseableElementTypeBase.java
index 95c60dee4640..35d9ebc674fa 100644
--- a/platform/core-api/src/com/intellij/psi/tree/ILazyParseableElementTypeBase.java
+++ b/platform/core-api/src/com/intellij/psi/tree/ILazyParseableElementTypeBase.java
@@ -16,11 +16,13 @@
 package com.intellij.psi.tree;
 
 import com.intellij.lang.ASTNode;
+import org.jetbrains.annotations.NotNull;
 
 /**
  * An additional interface to be implemented by {@link IElementType} instances for tokens which should be parsed lazily, but 
  * for some reasons extending {@link ILazyParseableElementType} is impossible.
  */
+@FunctionalInterface
 public interface ILazyParseableElementTypeBase {
   
   /**
@@ -30,5 +32,5 @@ public interface ILazyParseableElementTypeBase {
    * @param chameleon the node to parse.
    * @return the parsed contents of the node.
    */
-  ASTNode parseContents(ASTNode chameleon);
+  ASTNode parseContents(@NotNull ASTNode chameleon);
 }
diff --git a/platform/core-impl/src/com/intellij/openapi/fileTypes/PlainTextParserDefinition.java b/platform/core-impl/src/com/intellij/openapi/fileTypes/PlainTextParserDefinition.java
index 5be539039ecf..1db3132b6173 100644
--- a/platform/core-impl/src/com/intellij/openapi/fileTypes/PlainTextParserDefinition.java
+++ b/platform/core-impl/src/com/intellij/openapi/fileTypes/PlainTextParserDefinition.java
@@ -39,7 +39,7 @@ import org.jetbrains.annotations.NotNull;
 public class PlainTextParserDefinition implements ParserDefinition {
   private static final IFileElementType PLAIN_FILE_ELEMENT_TYPE = new IFileElementType(PlainTextFileType.INSTANCE.getLanguage()) {
     @Override
-    public ASTNode parseContents(ASTNode chameleon) {
+    public ASTNode parseContents(@NotNull ASTNode chameleon) {
       final CharSequence chars = chameleon.getChars();
       return ASTFactory.leaf(PlainTextTokenTypes.PLAIN_TEXT, chars);
     }
diff --git a/platform/core-impl/src/com/intellij/psi/PlainTextTokenTypes.java b/platform/core-impl/src/com/intellij/psi/PlainTextTokenTypes.java
index 86cac1a69d57..bba1f2a12466 100644
--- a/platform/core-impl/src/com/intellij/psi/PlainTextTokenTypes.java
+++ b/platform/core-impl/src/com/intellij/psi/PlainTextTokenTypes.java
@@ -21,11 +21,12 @@ import com.intellij.lang.ASTNode;
 import com.intellij.openapi.fileTypes.PlainTextLanguage;
 import com.intellij.psi.tree.IElementType;
 import com.intellij.psi.tree.IFileElementType;
+import org.jetbrains.annotations.NotNull;
 
 public class PlainTextTokenTypes {
   public static final IElementType PLAIN_TEXT_FILE = new IFileElementType("PLAIN_TEXT_FILE", PlainTextLanguage.INSTANCE) {
     @Override
-    public ASTNode parseContents(ASTNode chameleon) {
+    public ASTNode parseContents(@NotNull ASTNode chameleon) {
       return ASTFactory.leaf(PLAIN_TEXT, chameleon.getChars());
     }
   };
diff --git a/platform/lang-impl/src/com/intellij/psi/templateLanguages/TemplateDataElementType.java b/platform/lang-impl/src/com/intellij/psi/templateLanguages/TemplateDataElementType.java
index 275eb4de49fe..b4ef7b2b1990 100644
--- a/platform/lang-impl/src/com/intellij/psi/templateLanguages/TemplateDataElementType.java
+++ b/platform/lang-impl/src/com/intellij/psi/templateLanguages/TemplateDataElementType.java
@@ -72,7 +72,7 @@ public class TemplateDataElementType extends IFileElementType implements ITempla
   }
 
   @Override
-  public ASTNode parseContents(ASTNode chameleon) {
+  public ASTNode parseContents(@NotNull ASTNode chameleon) {
     final CharTable charTable = SharedImplUtil.findCharTableByTree(chameleon);
     final FileElement fileElement = TreeUtil.getFileElement((TreeElement)chameleon);
     final PsiFile psiFile = (PsiFile)fileElement.getPsi();
diff --git a/platform/platform-tests/testSrc/com/intellij/lang/PsiBuilderQuickTest.java b/platform/platform-tests/testSrc/com/intellij/lang/PsiBuilderQuickTest.java
index 1a4f89c6bcf0..4a642250d5e5 100644
--- a/platform/platform-tests/testSrc/com/intellij/lang/PsiBuilderQuickTest.java
+++ b/platform/platform-tests/testSrc/com/intellij/lang/PsiBuilderQuickTest.java
@@ -712,7 +712,7 @@ public class PsiBuilderQuickTest extends LightPlatformTestCase {
     }
 
     @Override
-    public ASTNode parseContents(ASTNode chameleon) {
+    public ASTNode parseContents(@NotNull ASTNode chameleon) {
       final PsiBuilder builder = createBuilder(chameleon.getText());
       parse(builder);
       return builder.getTreeBuilt().getFirstChildNode();
@@ -752,7 +752,7 @@ public class PsiBuilderQuickTest extends LightPlatformTestCase {
     }
 
     @Override
-    public ASTNode parseContents(ASTNode chameleon) {
+    public ASTNode parseContents(@NotNull ASTNode chameleon) {
       final PsiBuilder builder = createBuilder(chameleon.getText());
       parse(builder);
       return builder.getTreeBuilt().getFirstChildNode();
diff --git a/plugins/groovy/groovy-psi/src/org/jetbrains/plugins/groovy/lang/groovydoc/parser/GroovyDocElementTypes.java b/plugins/groovy/groovy-psi/src/org/jetbrains/plugins/groovy/lang/groovydoc/parser/GroovyDocElementTypes.java
index 13851d0b6195..da644cd5b5b7 100644
--- a/plugins/groovy/groovy-psi/src/org/jetbrains/plugins/groovy/lang/groovydoc/parser/GroovyDocElementTypes.java
+++ b/plugins/groovy/groovy-psi/src/org/jetbrains/plugins/groovy/lang/groovydoc/parser/GroovyDocElementTypes.java
@@ -44,7 +44,7 @@ public interface GroovyDocElementTypes {
     }
 
     @Override
-    public ASTNode parseContents(ASTNode chameleon) {
+    public ASTNode parseContents(@NotNull ASTNode chameleon) {
       final PsiElement parentElement = chameleon.getTreeParent().getPsi();
       final Project project = JavaPsiFacade.getInstance(parentElement.getProject()).getProject();
 
diff --git a/plugins/groovy/groovy-psi/src/org/jetbrains/plugins/groovy/lang/groovydoc/parser/elements/GroovyDocTagValueTokenType.java b/plugins/groovy/groovy-psi/src/org/jetbrains/plugins/groovy/lang/groovydoc/parser/elements/GroovyDocTagValueTokenType.java
index e4f087511abd..f2ab011ce8f5 100644
--- a/plugins/groovy/groovy-psi/src/org/jetbrains/plugins/groovy/lang/groovydoc/parser/elements/GroovyDocTagValueTokenType.java
+++ b/plugins/groovy/groovy-psi/src/org/jetbrains/plugins/groovy/lang/groovydoc/parser/elements/GroovyDocTagValueTokenType.java
@@ -63,7 +63,7 @@ public class GroovyDocTagValueTokenType extends GroovyDocChameleonElementType im
   }
 
   @Override
-  public ASTNode parseContents(ASTNode chameleon) {
+  public ASTNode parseContents(@NotNull ASTNode chameleon) {
     ASTNode parent = chameleon.getTreeParent();
     if (isReferenceElement(parent, chameleon)) {
       return parseImpl(chameleon);
diff --git a/python/src/com/jetbrains/python/psi/PyFileElementType.java b/python/src/com/jetbrains/python/psi/PyFileElementType.java
index 09aa53f61367..a6c77063fe7e 100644
--- a/python/src/com/jetbrains/python/psi/PyFileElementType.java
+++ b/python/src/com/jetbrains/python/psi/PyFileElementType.java
@@ -67,7 +67,7 @@ public class PyFileElementType extends IStubFileElementType<PyFileStub> {
 
   @Nullable
   @Override
-  public ASTNode parseContents(ASTNode node) {
+  public ASTNode parseContents(@NotNull ASTNode node) {
     final LanguageLevel languageLevel = getLanguageLevel(node.getPsi());
     if (PydevConsoleRunner.isPythonConsole(node)) {
       return parseConsoleCode(node, PydevConsoleRunner.getPythonConsoleData(node));