diff --git a/java/java-impl/src/com/intellij/codeInsight/hint/api/impls/ReferenceParameterInfoHandler.java b/java/java-impl/src/com/intellij/codeInsight/hint/api/impls/ReferenceParameterInfoHandler.java
index 899270929d7e..b1f882c6214d 100644
--- a/java/java-impl/src/com/intellij/codeInsight/hint/api/impls/ReferenceParameterInfoHandler.java
+++ b/java/java-impl/src/com/intellij/codeInsight/hint/api/impls/ReferenceParameterInfoHandler.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2009 JetBrains s.r.o.
+ * 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.
@@ -45,7 +45,7 @@ public class ReferenceParameterInfoHandler implements ParameterInfoHandler<PsiRe
   }
 
   @Override
-  public PsiReferenceParameterList findElementForParameterInfo(final CreateParameterInfoContext context) {
+  public PsiReferenceParameterList findElementForParameterInfo(@NotNull final CreateParameterInfoContext context) {
     final PsiReferenceParameterList referenceParameterList =
       ParameterInfoUtils.findParentOfType(context.getFile(), context.getOffset(), PsiReferenceParameterList.class);
 
@@ -66,18 +66,18 @@ public class ReferenceParameterInfoHandler implements ParameterInfoHandler<PsiRe
   }
 
   @Override
-  public void showParameterInfo(@NotNull final PsiReferenceParameterList element, final CreateParameterInfoContext context) {
+  public void showParameterInfo(@NotNull final PsiReferenceParameterList element, @NotNull final CreateParameterInfoContext context) {
     context.showHint(element, element.getTextRange().getStartOffset() + 1, this);
   }
 
   @Override
-  public PsiReferenceParameterList findElementForUpdatingParameterInfo(final UpdateParameterInfoContext context) {
+  public PsiReferenceParameterList findElementForUpdatingParameterInfo(@NotNull final UpdateParameterInfoContext context) {
     return ParameterInfoUtils.findParentOfType(context.getFile(), context.getOffset(), PsiReferenceParameterList.class);
   }
 
   @Override
-  public void updateParameterInfo(@NotNull final PsiReferenceParameterList o, final UpdateParameterInfoContext context) {
-    int index = ParameterInfoUtils.getCurrentParameterIndex(o.getNode(), context.getOffset(), JavaTokenType.COMMA);
+  public void updateParameterInfo(@NotNull final PsiReferenceParameterList parameterOwner, @NotNull final UpdateParameterInfoContext context) {
+    int index = ParameterInfoUtils.getCurrentParameterIndex(parameterOwner.getNode(), context.getOffset(), JavaTokenType.COMMA);
     context.setCurrentParameter(index);
     final Object[] objectsToView = context.getObjectsToView();
     context.setHighlightedParameter(index < objectsToView.length && index >= 0 ? (PsiElement)objectsToView[index]:null);
@@ -95,7 +95,7 @@ public class ReferenceParameterInfoHandler implements ParameterInfoHandler<PsiRe
   }
 
   @Override
-  public void updateUI(PsiTypeParameter o, ParameterInfoUIContext context) {
+  public void updateUI(PsiTypeParameter o, @NotNull ParameterInfoUIContext context) {
     updateTypeParameter(o, context);
   }
 
diff --git a/platform/lang-api/src/com/intellij/lang/parameterInfo/ParameterInfoHandler.java b/platform/lang-api/src/com/intellij/lang/parameterInfo/ParameterInfoHandler.java
index e492c776d497..2910a930ae67 100644
--- a/platform/lang-api/src/com/intellij/lang/parameterInfo/ParameterInfoHandler.java
+++ b/platform/lang-api/src/com/intellij/lang/parameterInfo/ParameterInfoHandler.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2009 JetBrains s.r.o.
+ * 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.
@@ -27,19 +27,20 @@ public interface ParameterInfoHandler <ParameterOwner, ParameterType> {
 
   // Find element for parameter info should also set ItemsToShow in context and may set highlighted element
   @Nullable
-  ParameterOwner findElementForParameterInfo(final CreateParameterInfoContext context);
+  ParameterOwner findElementForParameterInfo(@NotNull CreateParameterInfoContext context);
   // Usually context.showHint
-  void showParameterInfo(@NotNull final ParameterOwner element, final CreateParameterInfoContext context);
+  void showParameterInfo(@NotNull final ParameterOwner element, @NotNull CreateParameterInfoContext context);
 
   // Null returns leads to removing hint
   @Nullable
-  ParameterOwner findElementForUpdatingParameterInfo(final UpdateParameterInfoContext context);
-  void updateParameterInfo(@NotNull final ParameterOwner o, final UpdateParameterInfoContext context);
+  ParameterOwner findElementForUpdatingParameterInfo(@NotNull UpdateParameterInfoContext context);
+  void updateParameterInfo(@NotNull final ParameterOwner parameterOwner, @NotNull UpdateParameterInfoContext context);
 
   // Can be null if parameter info does not track parameter index
-  @Nullable String getParameterCloseChars();
+  @Nullable
+  String getParameterCloseChars();
   boolean tracksParameterIndex();
 
   // context.setEnabled / context.setupUIComponentPresentation
-  void updateUI(ParameterType p, ParameterInfoUIContext context);
+  void updateUI(ParameterType p, @NotNull ParameterInfoUIContext context);
 }
diff --git a/platform/lang-impl/src/com/intellij/codeInsight/TargetElementUtilBase.java b/platform/lang-impl/src/com/intellij/codeInsight/TargetElementUtilBase.java
index 59f2c99c9130..bc759ae1cfa0 100644
--- a/platform/lang-impl/src/com/intellij/codeInsight/TargetElementUtilBase.java
+++ b/platform/lang-impl/src/com/intellij/codeInsight/TargetElementUtilBase.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2012 JetBrains s.r.o.
+ * 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.
@@ -118,9 +118,6 @@ public class TargetElementUtilBase {
 
   /**
    * @deprecated adjust offset with PsiElement should be used instead to provide correct checking for identifier part
-   * @param document
-   * @param offset
-   * @return
    */
   public static int adjustOffset(Document document, final int offset) {
     return adjustOffset(null, document, offset);
diff --git a/plugins/groovy/src/org/jetbrains/plugins/groovy/lang/parameterInfo/GroovyAnnotationAttributeInfoHandler.java b/plugins/groovy/src/org/jetbrains/plugins/groovy/lang/parameterInfo/GroovyAnnotationAttributeInfoHandler.java
index 7a58e0d3de07..8d6705087992 100644
--- a/plugins/groovy/src/org/jetbrains/plugins/groovy/lang/parameterInfo/GroovyAnnotationAttributeInfoHandler.java
+++ b/plugins/groovy/src/org/jetbrains/plugins/groovy/lang/parameterInfo/GroovyAnnotationAttributeInfoHandler.java
@@ -154,7 +154,7 @@ public class GroovyAnnotationAttributeInfoHandler implements ParameterInfoHandle
   }
 
   @Override
-  public void updateParameterInfo(@NotNull GrAnnotationArgumentList o, @NotNull UpdateParameterInfoContext context) {
+  public void updateParameterInfo(@NotNull GrAnnotationArgumentList parameterOwner, @NotNull UpdateParameterInfoContext context) {
     context.setHighlightedParameter(findAnnotationMethod(context.getFile(), context.getEditor()));
   }
 
diff --git a/plugins/groovy/src/org/jetbrains/plugins/groovy/lang/parameterInfo/GroovyParameterInfoHandler.java b/plugins/groovy/src/org/jetbrains/plugins/groovy/lang/parameterInfo/GroovyParameterInfoHandler.java
index 0df8cf1329be..25ad76be2231 100644
--- a/plugins/groovy/src/org/jetbrains/plugins/groovy/lang/parameterInfo/GroovyParameterInfoHandler.java
+++ b/plugins/groovy/src/org/jetbrains/plugins/groovy/lang/parameterInfo/GroovyParameterInfoHandler.java
@@ -102,11 +102,11 @@ public class GroovyParameterInfoHandler implements ParameterInfoHandlerWithTabAc
     return ArrayUtil.EMPTY_OBJECT_ARRAY;
   }
 
-  public GroovyPsiElement findElementForParameterInfo(CreateParameterInfoContext context) {
+  public GroovyPsiElement findElementForParameterInfo(@NotNull CreateParameterInfoContext context) {
     return findAnchorElement(context.getEditor().getCaretModel().getOffset(), context.getFile());
   }
 
-  public GroovyPsiElement findElementForUpdatingParameterInfo(UpdateParameterInfoContext context) {
+  public GroovyPsiElement findElementForUpdatingParameterInfo(@NotNull UpdateParameterInfoContext context) {
     return findAnchorElement(context.getEditor().getCaretModel().getOffset(), context.getFile());
   }
 
@@ -210,7 +210,7 @@ public class GroovyParameterInfoHandler implements ParameterInfoHandlerWithTabAc
     return resolveResult.isInvokedOnProperty() || resolveResult.getElement() instanceof PsiVariable;
   }
 
-  public void updateParameterInfo(@NotNull GroovyPsiElement place, UpdateParameterInfoContext context) {
+  public void updateParameterInfo(@NotNull GroovyPsiElement place, @NotNull UpdateParameterInfoContext context) {
     final PsiElement parameterOwner = context.getParameterOwner();
     if (parameterOwner != place) {
       context.removeHint();
@@ -318,7 +318,7 @@ public class GroovyParameterInfoHandler implements ParameterInfoHandlerWithTabAc
     return true;
   }
 
-  public void updateUI(Object o, ParameterInfoUIContext context) {
+  public void updateUI(Object o, @NotNull ParameterInfoUIContext context) {
     CodeInsightSettings settings = CodeInsightSettings.getInstance();
 
     if (o == null) return;
diff --git a/plugins/groovy/src/org/jetbrains/plugins/groovy/lang/parameterInfo/GroovyTypeParameterInfoHandler.java b/plugins/groovy/src/org/jetbrains/plugins/groovy/lang/parameterInfo/GroovyTypeParameterInfoHandler.java
index 63560d25f0ec..4924d0175b33 100644
--- a/plugins/groovy/src/org/jetbrains/plugins/groovy/lang/parameterInfo/GroovyTypeParameterInfoHandler.java
+++ b/plugins/groovy/src/org/jetbrains/plugins/groovy/lang/parameterInfo/GroovyTypeParameterInfoHandler.java
@@ -100,7 +100,7 @@ public class GroovyTypeParameterInfoHandler implements ParameterInfoHandlerWithT
 
   @Nullable
   @Override
-  public GrTypeArgumentList findElementForParameterInfo(CreateParameterInfoContext context) {
+  public GrTypeArgumentList findElementForParameterInfo(@NotNull CreateParameterInfoContext context) {
     final GrTypeArgumentList parameterList = ParameterInfoUtils.findParentOfType(context.getFile(), context.getOffset(), GrTypeArgumentList.class);
 
     if (parameterList != null) {
@@ -121,19 +121,19 @@ public class GroovyTypeParameterInfoHandler implements ParameterInfoHandlerWithT
   }
 
   @Override
-  public void showParameterInfo(@NotNull GrTypeArgumentList element, CreateParameterInfoContext context) {
+  public void showParameterInfo(@NotNull GrTypeArgumentList element, @NotNull CreateParameterInfoContext context) {
     context.showHint(element, element.getTextRange().getStartOffset() + 1, this);
   }
 
   @Nullable
   @Override
-  public GrTypeArgumentList findElementForUpdatingParameterInfo(UpdateParameterInfoContext context) {
+  public GrTypeArgumentList findElementForUpdatingParameterInfo(@NotNull UpdateParameterInfoContext context) {
     return ParameterInfoUtils.findParentOfType(context.getFile(), context.getOffset(), GrTypeArgumentList.class);
   }
 
   @Override
-  public void updateParameterInfo(@NotNull GrTypeArgumentList o, UpdateParameterInfoContext context) {
-    int index = ParameterInfoUtils.getCurrentParameterIndex(o.getNode(), context.getOffset(), getActualParameterDelimiterType());
+  public void updateParameterInfo(@NotNull GrTypeArgumentList parameterOwner, @NotNull UpdateParameterInfoContext context) {
+    int index = ParameterInfoUtils.getCurrentParameterIndex(parameterOwner.getNode(), context.getOffset(), getActualParameterDelimiterType());
     context.setCurrentParameter(index);
     final Object[] objectsToView = context.getObjectsToView();
     context.setHighlightedParameter(index < objectsToView.length && index >= 0 ? (PsiElement)objectsToView[index] : null);
@@ -151,7 +151,7 @@ public class GroovyTypeParameterInfoHandler implements ParameterInfoHandlerWithT
   }
 
   @Override
-  public void updateUI(PsiTypeParameter p, ParameterInfoUIContext context) {
+  public void updateUI(PsiTypeParameter p, @NotNull ParameterInfoUIContext context) {
     @NonNls StringBuilder buffer = new StringBuilder();
     buffer.append(p.getName());
     int highlightEndOffset = buffer.length();
diff --git a/plugins/xpath/xpath-lang/src/org/intellij/lang/xpath/XPathParameterInfoHandler.java b/plugins/xpath/xpath-lang/src/org/intellij/lang/xpath/XPathParameterInfoHandler.java
index 7eb1e913a619..59df3329a9f4 100644
--- a/plugins/xpath/xpath-lang/src/org/intellij/lang/xpath/XPathParameterInfoHandler.java
+++ b/plugins/xpath/xpath-lang/src/org/intellij/lang/xpath/XPathParameterInfoHandler.java
@@ -43,7 +43,7 @@ public class XPathParameterInfoHandler implements ParameterInfoHandler<XPathFunc
       return ArrayUtil.EMPTY_OBJECT_ARRAY;
     }
 
-    public XPathFunctionCall findElementForParameterInfo(CreateParameterInfoContext context) {
+    public XPathFunctionCall findElementForParameterInfo(@NotNull CreateParameterInfoContext context) {
         final XPathFunctionCall call = findFunctionCall(context.getFile(), context.getOffset());
         if (call != null) {
             final XPathFunction function = call.resolve();
@@ -72,15 +72,15 @@ public class XPathParameterInfoHandler implements ParameterInfoHandler<XPathFunc
         return null;
     }
 
-    public void showParameterInfo(@NotNull XPathFunctionCall call, CreateParameterInfoContext context) {
+    public void showParameterInfo(@NotNull XPathFunctionCall call, @NotNull CreateParameterInfoContext context) {
         context.showHint(call, call.getTextOffset() + 1, this);
     }
 
-    public XPathFunctionCall findElementForUpdatingParameterInfo(UpdateParameterInfoContext context) {
+    public XPathFunctionCall findElementForUpdatingParameterInfo(@NotNull UpdateParameterInfoContext context) {
         return findFunctionCall(context.getFile(), context.getOffset());
     }
 
-    public void updateParameterInfo(@NotNull XPathFunctionCall call, UpdateParameterInfoContext context) {
+    public void updateParameterInfo(@NotNull XPathFunctionCall call, @NotNull UpdateParameterInfoContext context) {
         int currentParameterIndex = ParameterInfoUtils.getCurrentParameterIndex(call.getNode(), context.getOffset(), XPathTokenTypes.COMMA);
         context.setCurrentParameter(currentParameterIndex);
     }
@@ -93,7 +93,7 @@ public class XPathParameterInfoHandler implements ParameterInfoHandler<XPathFunc
         return true;
     }
 
-    public void updateUI(XPathFunction function, ParameterInfoUIContext context) {
+    public void updateUI(XPathFunction function, @NotNull ParameterInfoUIContext context) {
         final Function declaration = function.getDeclaration();
         if (declaration != null) {
             if (declaration.getParameters().length > 0) {
diff --git a/python/src/com/jetbrains/python/PyParameterInfoHandler.java b/python/src/com/jetbrains/python/PyParameterInfoHandler.java
index b3f99f2f6344..5aec4444193b 100644
--- a/python/src/com/jetbrains/python/PyParameterInfoHandler.java
+++ b/python/src/com/jetbrains/python/PyParameterInfoHandler.java
@@ -51,7 +51,7 @@ public class PyParameterInfoHandler implements ParameterInfoHandler<PyArgumentLi
     return ArrayUtil.EMPTY_OBJECT_ARRAY;  // we don't
   }
 
-  public PyArgumentList findElementForParameterInfo(final CreateParameterInfoContext context) {
+  public PyArgumentList findElementForParameterInfo(@NotNull final CreateParameterInfoContext context) {
     PyArgumentList arglist = findArgumentList(context);
     if (arglist != null) {
       final TypeEvalContext typeEvalContext = TypeEvalContext.userInitiated(arglist.getContainingFile());
@@ -69,11 +69,11 @@ public class PyParameterInfoHandler implements ParameterInfoHandler<PyArgumentLi
     return ParameterInfoUtils.findParentOfType(context.getFile(), context.getOffset(), PyArgumentList.class);
   }
 
-  public void showParameterInfo(@NotNull final PyArgumentList element, final CreateParameterInfoContext context) {
+  public void showParameterInfo(@NotNull final PyArgumentList element, @NotNull final CreateParameterInfoContext context) {
     context.showHint(element, element.getTextOffset(), this);
   }
 
-  public PyArgumentList findElementForUpdatingParameterInfo(final UpdateParameterInfoContext context) {
+  public PyArgumentList findElementForUpdatingParameterInfo(@NotNull final UpdateParameterInfoContext context) {
     return findArgumentList(context);
   }
 
@@ -82,7 +82,7 @@ public class PyParameterInfoHandler implements ParameterInfoHandler<PyArgumentLi
    We cannot store an index since we cannot determine what is an argument until we actually map arguments to parameters.
    This is because a tuple in arguments may be a whole argument or map to a tuple parameter.
    */
-  public void updateParameterInfo(@NotNull final PyArgumentList arglist, final UpdateParameterInfoContext context) {
+  public void updateParameterInfo(@NotNull final PyArgumentList arglist, @NotNull final UpdateParameterInfoContext context) {
     if (context.getParameterOwner() != arglist) {
       context.removeHint();
       return;
@@ -125,7 +125,7 @@ public class PyParameterInfoHandler implements ParameterInfoHandler<PyArgumentLi
   }
 
   @Override
-  public void updateUI(final CallArgumentsMapping prevResult, final ParameterInfoUIContext context) {
+  public void updateUI(final CallArgumentsMapping prevResult, @NotNull final ParameterInfoUIContext context) {
     if (prevResult == null) return;
     final PyArgumentList argList = prevResult.getArgumentList();
     if (!argList.isValid()) return;
diff --git a/xml/impl/src/com/intellij/codeInsight/hint/api/impls/XmlParameterInfoHandler.java b/xml/impl/src/com/intellij/codeInsight/hint/api/impls/XmlParameterInfoHandler.java
index 798a3d9db737..087943d56b33 100644
--- a/xml/impl/src/com/intellij/codeInsight/hint/api/impls/XmlParameterInfoHandler.java
+++ b/xml/impl/src/com/intellij/codeInsight/hint/api/impls/XmlParameterInfoHandler.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2009 JetBrains s.r.o.
+ * 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.
@@ -67,7 +67,7 @@ public class XmlParameterInfoHandler implements ParameterInfoHandler<XmlTag,XmlE
     return true;
   }
 
-  public XmlTag findElementForParameterInfo(final CreateParameterInfoContext context) {
+  public XmlTag findElementForParameterInfo(@NotNull final CreateParameterInfoContext context) {
     final XmlTag tag = findXmlTag(context.getFile(), context.getOffset());
     final XmlElementDescriptor descriptor = tag != null ? tag.getDescriptor() : null;
 
@@ -80,11 +80,11 @@ public class XmlParameterInfoHandler implements ParameterInfoHandler<XmlTag,XmlE
     return tag;
   }
 
-  public void showParameterInfo(final @NotNull XmlTag element, final CreateParameterInfoContext context) {
+  public void showParameterInfo(final @NotNull XmlTag element, @NotNull final CreateParameterInfoContext context) {
     context.showHint(element, element.getTextRange().getStartOffset() + 1, this);
   }
 
-  public XmlTag findElementForUpdatingParameterInfo(final UpdateParameterInfoContext context) {
+  public XmlTag findElementForUpdatingParameterInfo(@NotNull final UpdateParameterInfoContext context) {
     final XmlTag tag = findXmlTag(context.getFile(), context.getOffset());
     if (tag != null) {
       final PsiElement currentXmlTag = context.getParameterOwner();
@@ -94,9 +94,9 @@ public class XmlParameterInfoHandler implements ParameterInfoHandler<XmlTag,XmlE
     return null;
   }
 
-  public void updateParameterInfo(@NotNull final XmlTag o, final UpdateParameterInfoContext context) {
-    if (context.getParameterOwner() == null || o.equals(context.getParameterOwner())) {
-      context.setParameterOwner( o );
+  public void updateParameterInfo(@NotNull final XmlTag parameterOwner, @NotNull final UpdateParameterInfoContext context) {
+    if (context.getParameterOwner() == null || parameterOwner.equals(context.getParameterOwner())) {
+      context.setParameterOwner(parameterOwner);
     } else {
       context.removeHint();
     }
@@ -145,7 +145,7 @@ public class XmlParameterInfoHandler implements ParameterInfoHandler<XmlTag,XmlE
     return null;
   }
 
-  public void updateUI(XmlElementDescriptor o, final ParameterInfoUIContext context) {
+  public void updateUI(XmlElementDescriptor o, @NotNull final ParameterInfoUIContext context) {
     updateElementDescriptor(
       o,
       context,