diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/psi/JetExpressionCodeFragmentType.java b/compiler/frontend/src/org/jetbrains/jet/lang/psi/JetExpressionCodeFragmentType.java
index 03d1b30bfbb..1bbf39021b6 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/psi/JetExpressionCodeFragmentType.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/psi/JetExpressionCodeFragmentType.java
@@ -33,6 +33,7 @@ public class JetExpressionCodeFragmentType extends JetFileElementType {
         super(NAME);
     }
 
+    @NotNull
     @Override
     public String getExternalId() {
         return NAME;
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/psi/JetTypeCodeFragmentType.java b/compiler/frontend/src/org/jetbrains/jet/lang/psi/JetTypeCodeFragmentType.java
index 1e538cff514..2397ac71fe0 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/psi/JetTypeCodeFragmentType.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/psi/JetTypeCodeFragmentType.java
@@ -33,6 +33,7 @@ public class JetTypeCodeFragmentType extends JetFileElementType {
         super(NAME);
     }
 
+    @NotNull
     @Override
     public String getExternalId() {
         return NAME;
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetAnnotationElementType.java b/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetAnnotationElementType.java
index a4fb74d67f8..40c817beb33 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetAnnotationElementType.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetAnnotationElementType.java
@@ -55,18 +55,19 @@ public class JetAnnotationElementType extends JetStubElementType<PsiJetAnnotatio
     }
 
     @Override
-    public void serialize(PsiJetAnnotationStub stub, StubOutputStream dataStream) throws IOException {
+    public void serialize(@NotNull PsiJetAnnotationStub stub, @NotNull StubOutputStream dataStream) throws IOException {
         dataStream.writeName(stub.getShortName());
     }
 
+    @NotNull
     @Override
-    public PsiJetAnnotationStub deserialize(StubInputStream dataStream, StubElement parentStub) throws IOException {
+    public PsiJetAnnotationStub deserialize(@NotNull StubInputStream dataStream, StubElement parentStub) throws IOException {
         StringRef text = dataStream.readName();
         return new PsiJetAnnotationStubImpl(parentStub, JetStubElementTypes.ANNOTATION_ENTRY, text);
     }
 
     @Override
-    public void indexStub(PsiJetAnnotationStub stub, IndexSink sink) {
+    public void indexStub(@NotNull PsiJetAnnotationStub stub, @NotNull IndexSink sink) {
         StubIndexServiceFactory.getInstance().indexAnnotation(stub, sink);
     }
 }
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetClassElementType.java b/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetClassElementType.java
index 06571a4b7bd..eff2479e849 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetClassElementType.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetClassElementType.java
@@ -59,7 +59,7 @@ public class JetClassElementType extends JetStubElementType<PsiJetClassStub, Jet
     }
 
     @Override
-    public void serialize(PsiJetClassStub stub, StubOutputStream dataStream) throws IOException {
+    public void serialize(@NotNull PsiJetClassStub stub, @NotNull StubOutputStream dataStream) throws IOException {
         dataStream.writeName(stub.getName());
         FqName fqName = stub.getFqName();
         dataStream.writeName(fqName == null ? null : fqName.asString());
@@ -76,8 +76,9 @@ public class JetClassElementType extends JetStubElementType<PsiJetClassStub, Jet
         }
     }
 
+    @NotNull
     @Override
-    public PsiJetClassStub deserialize(StubInputStream dataStream, StubElement parentStub) throws IOException {
+    public PsiJetClassStub deserialize(@NotNull StubInputStream dataStream, StubElement parentStub) throws IOException {
         StringRef name = dataStream.readName();
         StringRef qualifiedName = dataStream.readName();
         boolean isTrait = dataStream.readBoolean();
@@ -97,7 +98,7 @@ public class JetClassElementType extends JetStubElementType<PsiJetClassStub, Jet
     }
 
     @Override
-    public void indexStub(PsiJetClassStub stub, IndexSink sink) {
+    public void indexStub(@NotNull PsiJetClassStub stub, @NotNull IndexSink sink) {
         StubIndexServiceFactory.getInstance().indexClass(stub, sink);
     }
 
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetFileElementType.java b/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetFileElementType.java
index 94e4574f722..3f12a5eee42 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetFileElementType.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetFileElementType.java
@@ -56,20 +56,22 @@ public class JetFileElementType extends IStubFileElementType<PsiJetFileStub> {
         return STUB_VERSION;
     }
 
+    @NotNull
     @Override
     public String getExternalId() {
         return "jet.FILE";
     }
 
     @Override
-    public void serialize(PsiJetFileStub stub, StubOutputStream dataStream)
+    public void serialize(@NotNull PsiJetFileStub stub, @NotNull StubOutputStream dataStream)
             throws IOException {
         dataStream.writeName(stub.getPackageName());
         dataStream.writeBoolean(stub.isScript());
     }
 
+    @NotNull
     @Override
-    public PsiJetFileStub deserialize(StubInputStream dataStream, StubElement parentStub) throws IOException {
+    public PsiJetFileStub deserialize(@NotNull StubInputStream dataStream, StubElement parentStub) throws IOException {
         StringRef packName = dataStream.readName();
         boolean isScript = dataStream.readBoolean();
         return new PsiJetFileStubImpl(null, packName, isScript);
@@ -85,7 +87,7 @@ public class JetFileElementType extends IStubFileElementType<PsiJetFileStub> {
     }
 
     @Override
-    public void indexStub(PsiJetFileStub stub, IndexSink sink) {
+    public void indexStub(@NotNull PsiJetFileStub stub, @NotNull IndexSink sink) {
         StubIndexServiceFactory.getInstance().indexFile(stub, sink);
     }
 }
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetFunctionElementType.java b/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetFunctionElementType.java
index 31dbf10bfdb..0f90cf79e2a 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetFunctionElementType.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetFunctionElementType.java
@@ -73,7 +73,7 @@ public class JetFunctionElementType extends JetStubElementType<PsiJetFunctionStu
     }
 
     @Override
-    public void serialize(PsiJetFunctionStub stub, StubOutputStream dataStream) throws IOException {
+    public void serialize(@NotNull PsiJetFunctionStub stub, @NotNull StubOutputStream dataStream) throws IOException {
         dataStream.writeName(stub.getName());
         dataStream.writeBoolean(stub.isTopLevel());
 
@@ -83,8 +83,9 @@ public class JetFunctionElementType extends JetStubElementType<PsiJetFunctionStu
         dataStream.writeBoolean(stub.isExtension());
     }
 
+    @NotNull
     @Override
-    public PsiJetFunctionStub deserialize(StubInputStream dataStream, StubElement parentStub) throws IOException {
+    public PsiJetFunctionStub deserialize(@NotNull StubInputStream dataStream, StubElement parentStub) throws IOException {
         StringRef name = dataStream.readName();
         boolean isTopLevel = dataStream.readBoolean();
 
@@ -97,7 +98,7 @@ public class JetFunctionElementType extends JetStubElementType<PsiJetFunctionStu
     }
 
     @Override
-    public void indexStub(PsiJetFunctionStub stub, IndexSink sink) {
+    public void indexStub(@NotNull PsiJetFunctionStub stub, @NotNull IndexSink sink) {
         StubIndexServiceFactory.getInstance().indexFunction(stub, sink);
     }
 }
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetObjectElementType.java b/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetObjectElementType.java
index 7d8a1aa8814..4fe27414d46 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetObjectElementType.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetObjectElementType.java
@@ -69,7 +69,7 @@ public class JetObjectElementType extends JetStubElementType<PsiJetObjectStub, J
     }
 
     @Override
-    public void serialize(PsiJetObjectStub stub, StubOutputStream dataStream) throws IOException {
+    public void serialize(@NotNull PsiJetObjectStub stub, @NotNull StubOutputStream dataStream) throws IOException {
         dataStream.writeName(stub.getName());
         FqName fqName = stub.getFqName();
         dataStream.writeName(fqName != null ? fqName.toString() : null);
@@ -77,8 +77,9 @@ public class JetObjectElementType extends JetStubElementType<PsiJetObjectStub, J
         dataStream.writeBoolean(stub.isClassObject());
     }
 
+    @NotNull
     @Override
-    public PsiJetObjectStub deserialize(StubInputStream dataStream, StubElement parentStub) throws IOException {
+    public PsiJetObjectStub deserialize(@NotNull StubInputStream dataStream, StubElement parentStub) throws IOException {
         StringRef name = dataStream.readName();
         StringRef fqNameStr = dataStream.readName();
         FqName fqName = fqNameStr != null ? new FqName(fqNameStr.toString()) : null;
@@ -89,7 +90,7 @@ public class JetObjectElementType extends JetStubElementType<PsiJetObjectStub, J
     }
 
     @Override
-    public void indexStub(PsiJetObjectStub stub, IndexSink sink) {
+    public void indexStub(@NotNull PsiJetObjectStub stub, @NotNull IndexSink sink) {
         StubIndexServiceFactory.getInstance().indexObject(stub, sink);
     }
 
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetParameterElementType.java b/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetParameterElementType.java
index 77ce62d7876..74009e0ea26 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetParameterElementType.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetParameterElementType.java
@@ -64,7 +64,7 @@ public class JetParameterElementType extends JetStubElementType<PsiJetParameterS
     }
 
     @Override
-    public void serialize(PsiJetParameterStub stub, StubOutputStream dataStream) throws IOException {
+    public void serialize(@NotNull PsiJetParameterStub stub, @NotNull StubOutputStream dataStream) throws IOException {
         dataStream.writeName(stub.getName());
         dataStream.writeBoolean(stub.isMutable());
         dataStream.writeBoolean(stub.isVarArg());
@@ -72,8 +72,9 @@ public class JetParameterElementType extends JetStubElementType<PsiJetParameterS
         dataStream.writeName(stub.getDefaultValueText());
     }
 
+    @NotNull
     @Override
-    public PsiJetParameterStub deserialize(StubInputStream dataStream, StubElement parentStub) throws IOException {
+    public PsiJetParameterStub deserialize(@NotNull StubInputStream dataStream, StubElement parentStub) throws IOException {
         StringRef name = dataStream.readName();
         boolean isMutable = dataStream.readBoolean();
         boolean isVarArg = dataStream.readBoolean();
@@ -85,7 +86,7 @@ public class JetParameterElementType extends JetStubElementType<PsiJetParameterS
     }
 
     @Override
-    public void indexStub(PsiJetParameterStub stub, IndexSink sink) {
+    public void indexStub(@NotNull PsiJetParameterStub stub, @NotNull IndexSink sink) {
         // No index
     }
 }
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetParameterListElementType.java b/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetParameterListElementType.java
index 4b1e000cb37..41d265f4cbf 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetParameterListElementType.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetParameterListElementType.java
@@ -50,17 +50,18 @@ public class JetParameterListElementType extends JetStubElementType<PsiJetParame
     }
 
     @Override
-    public void serialize(PsiJetParameterListStub stub, StubOutputStream dataStream) throws IOException {
+    public void serialize(@NotNull PsiJetParameterListStub stub, @NotNull StubOutputStream dataStream) throws IOException {
         // Nothing to serialize
     }
 
+    @NotNull
     @Override
-    public PsiJetParameterListStub deserialize(StubInputStream dataStream, StubElement parentStub) throws IOException {
+    public PsiJetParameterListStub deserialize(@NotNull StubInputStream dataStream, StubElement parentStub) throws IOException {
         return new PsiJetParameterListStubImpl(JetStubElementTypes.VALUE_PARAMETER_LIST, parentStub);
     }
 
     @Override
-    public void indexStub(PsiJetParameterListStub stub, IndexSink sink) {
+    public void indexStub(@NotNull PsiJetParameterListStub stub, @NotNull IndexSink sink) {
         // No index
     }
 }
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetPropertyElementType.java b/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetPropertyElementType.java
index 89a31dc990b..640480a70e8 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetPropertyElementType.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetPropertyElementType.java
@@ -79,7 +79,7 @@ public class JetPropertyElementType extends JetStubElementType<PsiJetPropertyStu
     }
 
     @Override
-    public void serialize(PsiJetPropertyStub stub, StubOutputStream dataStream) throws IOException {
+    public void serialize(@NotNull PsiJetPropertyStub stub, @NotNull StubOutputStream dataStream) throws IOException {
         dataStream.writeName(stub.getName());
         dataStream.writeBoolean(stub.isVar());
         dataStream.writeBoolean(stub.isTopLevel());
@@ -91,8 +91,9 @@ public class JetPropertyElementType extends JetStubElementType<PsiJetPropertyStu
         dataStream.writeName(stub.getInferenceBodyText());
     }
 
+    @NotNull
     @Override
-    public PsiJetPropertyStub deserialize(StubInputStream dataStream, StubElement parentStub) throws IOException {
+    public PsiJetPropertyStub deserialize(@NotNull StubInputStream dataStream, StubElement parentStub) throws IOException {
         StringRef name = dataStream.readName();
         boolean isVar = dataStream.readBoolean();
         boolean isTopLevel = dataStream.readBoolean();
@@ -108,7 +109,7 @@ public class JetPropertyElementType extends JetStubElementType<PsiJetPropertyStu
     }
 
     @Override
-    public void indexStub(PsiJetPropertyStub stub, IndexSink sink) {
+    public void indexStub(@NotNull PsiJetPropertyStub stub, @NotNull IndexSink sink) {
         StubIndexServiceFactory.getInstance().indexProperty(stub, sink);
     }
 }
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetStubElementType.java b/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetStubElementType.java
index 4cddb31a310..7732fbc6ec9 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetStubElementType.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetStubElementType.java
@@ -34,6 +34,7 @@ public abstract class JetStubElementType<StubT extends StubElement, PsiT extends
 
     public abstract PsiT createPsiFromAst(@NotNull ASTNode node);
 
+    @NotNull
     @Override
     public String getExternalId() {
         return "jet." + toString();
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetTypeParameterElementType.java b/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetTypeParameterElementType.java
index 487cb27cbdd..93360e2f792 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetTypeParameterElementType.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetTypeParameterElementType.java
@@ -58,15 +58,16 @@ public class JetTypeParameterElementType extends JetStubElementType<PsiJetTypePa
     }
 
     @Override
-    public void serialize(PsiJetTypeParameterStub stub, StubOutputStream dataStream) throws IOException {
+    public void serialize(@NotNull PsiJetTypeParameterStub stub, @NotNull StubOutputStream dataStream) throws IOException {
         dataStream.writeName(stub.getName());
         dataStream.writeName(stub.getExtendBoundTypeText());
         dataStream.writeBoolean(stub.isInVariance());
         dataStream.writeBoolean(stub.isOutVariance());
     }
 
+    @NotNull
     @Override
-    public PsiJetTypeParameterStub deserialize(StubInputStream dataStream, StubElement parentStub) throws IOException {
+    public PsiJetTypeParameterStub deserialize(@NotNull StubInputStream dataStream, StubElement parentStub) throws IOException {
         StringRef name = dataStream.readName();
         StringRef extendBoundTypeText = dataStream.readName();
         boolean isInVariance = dataStream.readBoolean();
@@ -77,7 +78,7 @@ public class JetTypeParameterElementType extends JetStubElementType<PsiJetTypePa
     }
 
     @Override
-    public void indexStub(PsiJetTypeParameterStub stub, IndexSink sink) {
+    public void indexStub(@NotNull PsiJetTypeParameterStub stub, @NotNull IndexSink sink) {
         // No index
     }
 }
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetTypeParameterListElementType.java b/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetTypeParameterListElementType.java
index 8c3fb9a1c90..2f79fc0aa8b 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetTypeParameterListElementType.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/psi/stubs/elements/JetTypeParameterListElementType.java
@@ -50,17 +50,18 @@ public class JetTypeParameterListElementType extends JetStubElementType<PsiJetTy
     }
 
     @Override
-    public void serialize(PsiJetTypeParameterListStub stub, StubOutputStream dataStream) throws IOException {
+    public void serialize(@NotNull PsiJetTypeParameterListStub stub, @NotNull StubOutputStream dataStream) throws IOException {
         // Do nothing
     }
 
+    @NotNull
     @Override
-    public PsiJetTypeParameterListStub deserialize(StubInputStream dataStream, StubElement parentStub) throws IOException {
+    public PsiJetTypeParameterListStub deserialize(@NotNull StubInputStream dataStream, StubElement parentStub) throws IOException {
         return new PsiJetTypeParameterListStubImpl(JetStubElementTypes.TYPE_PARAMETER_LIST, parentStub);
     }
 
     @Override
-    public void indexStub(PsiJetTypeParameterListStub stub, IndexSink sink) {
+    public void indexStub(@NotNull PsiJetTypeParameterListStub stub, @NotNull IndexSink sink) {
         // No index
     }
 }