diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/ImplementationBodyCodegen.java b/compiler/backend/src/org/jetbrains/jet/codegen/ImplementationBodyCodegen.java
index d14e07ad36d..216c487abca 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/ImplementationBodyCodegen.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/ImplementationBodyCodegen.java
@@ -1324,12 +1324,12 @@ public class ImplementationBodyCodegen extends ClassBodyCodegen {
     private void lookupConstructorExpressionsInClosureIfPresent(final ConstructorContext constructorContext) {
         JetVisitorVoid visitor = new JetVisitorVoid() {
             @Override
-            public void visitJetElement(JetElement e) {
+            public void visitJetElement(@NotNull JetElement e) {
                 e.acceptChildren(this);
             }
 
             @Override
-            public void visitSimpleNameExpression(JetSimpleNameExpression expr) {
+            public void visitSimpleNameExpression(@NotNull JetSimpleNameExpression expr) {
                 DeclarationDescriptor descriptor = bindingContext.get(BindingContext.REFERENCE_TARGET, expr);
                 if (descriptor instanceof VariableDescriptor && !(descriptor instanceof PropertyDescriptor)) {
                     ConstructorDescriptor constructorDescriptor = (ConstructorDescriptor) constructorContext.getContextDescriptor();
@@ -1355,7 +1355,7 @@ public class ImplementationBodyCodegen extends ClassBodyCodegen {
             }
 
             @Override
-            public void visitThisExpression(JetThisExpression expression) {
+            public void visitThisExpression(@NotNull JetThisExpression expression) {
                 DeclarationDescriptor descriptor = bindingContext.get(BindingContext.REFERENCE_TARGET, expression.getInstanceReference());
                 assert descriptor instanceof CallableDescriptor ||
                        descriptor instanceof ClassDescriptor : "'This' reference target should be class or callable descriptor but was " + descriptor;
diff --git a/compiler/backend/src/org/jetbrains/jet/codegen/binding/CodegenAnnotatingVisitor.java b/compiler/backend/src/org/jetbrains/jet/codegen/binding/CodegenAnnotatingVisitor.java
index 20ee44dad04..1d940689e91 100644
--- a/compiler/backend/src/org/jetbrains/jet/codegen/binding/CodegenAnnotatingVisitor.java
+++ b/compiler/backend/src/org/jetbrains/jet/codegen/binding/CodegenAnnotatingVisitor.java
@@ -139,13 +139,13 @@ class CodegenAnnotatingVisitor extends JetVisitorVoid {
     }
 
     @Override
-    public void visitJetElement(JetElement element) {
+    public void visitJetElement(@NotNull JetElement element) {
         super.visitJetElement(element);
         element.acceptChildren(this);
     }
 
     @Override
-    public void visitJetFile(JetFile file) {
+    public void visitJetFile(@NotNull JetFile file) {
         if (file.isScript()) {
             //noinspection ConstantConditions
             ClassDescriptor classDescriptor = bindingContext.get(CLASS_FOR_SCRIPT, bindingContext.get(SCRIPT, file.getScript()));
@@ -164,7 +164,7 @@ class CodegenAnnotatingVisitor extends JetVisitorVoid {
     }
 
     @Override
-    public void visitEnumEntry(JetEnumEntry enumEntry) {
+    public void visitEnumEntry(@NotNull JetEnumEntry enumEntry) {
         ClassDescriptor descriptor = bindingContext.get(CLASS, enumEntry);
         assert descriptor != null;
 
@@ -181,7 +181,7 @@ class CodegenAnnotatingVisitor extends JetVisitorVoid {
     }
 
     @Override
-    public void visitClassObject(JetClassObject classObject) {
+    public void visitClassObject(@NotNull JetClassObject classObject) {
         ClassDescriptor classDescriptor = bindingContext.get(CLASS, classObject.getObjectDeclaration());
         assert classDescriptor != null;
 
@@ -196,7 +196,7 @@ class CodegenAnnotatingVisitor extends JetVisitorVoid {
     }
 
     @Override
-    public void visitObjectDeclaration(JetObjectDeclaration declaration) {
+    public void visitObjectDeclaration(@NotNull JetObjectDeclaration declaration) {
         if (declaration.getParent() instanceof JetObjectLiteralExpression || declaration.getParent() instanceof JetClassObject) {
             super.visitObjectDeclaration(declaration);
         }
@@ -217,7 +217,7 @@ class CodegenAnnotatingVisitor extends JetVisitorVoid {
     }
 
     @Override
-    public void visitClass(JetClass klass) {
+    public void visitClass(@NotNull JetClass klass) {
         ClassDescriptor classDescriptor = bindingContext.get(CLASS, klass);
         // working around a problem with shallow analysis
         if (classDescriptor == null) return;
@@ -239,7 +239,7 @@ class CodegenAnnotatingVisitor extends JetVisitorVoid {
     }
 
     @Override
-    public void visitObjectLiteralExpression(JetObjectLiteralExpression expression) {
+    public void visitObjectLiteralExpression(@NotNull JetObjectLiteralExpression expression) {
         ClassDescriptor classDescriptor = bindingContext.get(CLASS, expression.getObjectDeclaration());
         if (classDescriptor == null) {
             // working around a problem with shallow analysis
@@ -259,7 +259,7 @@ class CodegenAnnotatingVisitor extends JetVisitorVoid {
     }
 
     @Override
-    public void visitFunctionLiteralExpression(JetFunctionLiteralExpression expression) {
+    public void visitFunctionLiteralExpression(@NotNull JetFunctionLiteralExpression expression) {
         JetFunctionLiteral functionLiteral = expression.getFunctionLiteral();
         FunctionDescriptor functionDescriptor =
                 (FunctionDescriptor) bindingContext.get(DECLARATION_TO_DESCRIPTOR, functionLiteral);
@@ -298,7 +298,7 @@ class CodegenAnnotatingVisitor extends JetVisitorVoid {
     }
 
     @Override
-    public void visitDelegationToSuperCallSpecifier(JetDelegatorToSuperCall call) {
+    public void visitDelegationToSuperCallSpecifier(@NotNull JetDelegatorToSuperCall call) {
         ClassDescriptorWithState state = peekFromStack(classStack);
         assert state != null : "Class descriptor should be recorded before " + call + " processing";
         state.setDelegationToSuperCall(true);
@@ -307,7 +307,7 @@ class CodegenAnnotatingVisitor extends JetVisitorVoid {
     }
 
     @Override
-    public void visitCallableReferenceExpression(JetCallableReferenceExpression expression) {
+    public void visitCallableReferenceExpression(@NotNull JetCallableReferenceExpression expression) {
         FunctionDescriptor functionDescriptor = bindingContext.get(FUNCTION, expression);
         // working around a problem with shallow analysis
         if (functionDescriptor == null) return;
@@ -339,7 +339,7 @@ class CodegenAnnotatingVisitor extends JetVisitorVoid {
     }
 
     @Override
-    public void visitProperty(JetProperty property) {
+    public void visitProperty(@NotNull JetProperty property) {
         DeclarationDescriptor propertyDescriptor = bindingContext.get(DECLARATION_TO_DESCRIPTOR, property);
         // working around a problem with shallow analysis
         if (propertyDescriptor == null) return;
@@ -356,7 +356,7 @@ class CodegenAnnotatingVisitor extends JetVisitorVoid {
     }
 
     @Override
-    public void visitNamedFunction(JetNamedFunction function) {
+    public void visitNamedFunction(@NotNull JetNamedFunction function) {
         FunctionDescriptor functionDescriptor = (FunctionDescriptor) bindingContext.get(DECLARATION_TO_DESCRIPTOR, function);
         // working around a problem with shallow analysis
         if (functionDescriptor == null) return;
@@ -402,7 +402,7 @@ class CodegenAnnotatingVisitor extends JetVisitorVoid {
     }
 
     @Override
-    public void visitCallExpression(JetCallExpression expression) {
+    public void visitCallExpression(@NotNull JetCallExpression expression) {
         super.visitCallExpression(expression);
         ResolvedCall<? extends CallableDescriptor> call = bindingContext.get(BindingContext.RESOLVED_CALL, expression.getCalleeExpression());
         if (call == null) {
@@ -437,7 +437,7 @@ class CodegenAnnotatingVisitor extends JetVisitorVoid {
     }
 
     @Override
-    public void visitBinaryExpression(JetBinaryExpression expression) {
+    public void visitBinaryExpression(@NotNull JetBinaryExpression expression) {
         super.visitBinaryExpression(expression);
 
         FunctionDescriptor operationDescriptor =
@@ -460,7 +460,7 @@ class CodegenAnnotatingVisitor extends JetVisitorVoid {
     }
 
     @Override
-    public void visitArrayAccessExpression(JetArrayAccessExpression expression) {
+    public void visitArrayAccessExpression(@NotNull JetArrayAccessExpression expression) {
         super.visitArrayAccessExpression(expression);
 
         FunctionDescriptor operationDescriptor = (FunctionDescriptor) bindingContext.get(BindingContext.REFERENCE_TARGET, expression);
diff --git a/compiler/frontend/src/org/jetbrains/jet/checkers/DebugInfoUtil.java b/compiler/frontend/src/org/jetbrains/jet/checkers/DebugInfoUtil.java
index d076310cc14..fb2c607005d 100644
--- a/compiler/frontend/src/org/jetbrains/jet/checkers/DebugInfoUtil.java
+++ b/compiler/frontend/src/org/jetbrains/jet/checkers/DebugInfoUtil.java
@@ -83,7 +83,7 @@ public class DebugInfoUtil {
         root.acceptChildren(new JetTreeVisitorVoid() {
 
             @Override
-            public void visitReferenceExpression(JetReferenceExpression expression) {
+            public void visitReferenceExpression(@NotNull JetReferenceExpression expression) {
                 super.visitReferenceExpression(expression);
                 if (!BindingContextUtils.isExpressionWithValidReference(expression, bindingContext)){
                     return;
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/JetControlFlowProcessor.java b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/JetControlFlowProcessor.java
index 0427d825e38..8f5291f9c23 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/JetControlFlowProcessor.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/JetControlFlowProcessor.java
@@ -95,31 +95,31 @@ public class JetControlFlowProcessor {
         private final JetVisitorVoid conditionVisitor = new JetVisitorVoid() {
 
             @Override
-            public void visitWhenConditionInRange(JetWhenConditionInRange condition) {
+            public void visitWhenConditionInRange(@NotNull JetWhenConditionInRange condition) {
                 generateInstructions(condition.getRangeExpression(), CFPVisitor.this.inCondition); // TODO : inCondition?
                 generateInstructions(condition.getOperationReference(), CFPVisitor.this.inCondition); // TODO : inCondition?
                 // TODO : read the call to contains()...
             }
 
             @Override
-            public void visitWhenConditionIsPattern(JetWhenConditionIsPattern condition) {
+            public void visitWhenConditionIsPattern(@NotNull JetWhenConditionIsPattern condition) {
                 // TODO: types in CF?
             }
 
             @Override
-            public void visitWhenConditionWithExpression(JetWhenConditionWithExpression condition) {
+            public void visitWhenConditionWithExpression(@NotNull JetWhenConditionWithExpression condition) {
                 generateInstructions(condition.getExpression(), inCondition);
             }
 
             @Override
-            public void visitJetElement(JetElement element) {
+            public void visitJetElement(@NotNull JetElement element) {
                 throw new UnsupportedOperationException("[JetControlFlowProcessor] " + element.toString());
             }
         };
         private final JetVisitorVoid patternVisitor = new JetVisitorVoid() {
 
             @Override
-            public void visitJetElement(JetElement element) {
+            public void visitJetElement(@NotNull JetElement element) {
                 throw new UnsupportedOperationException("[JetControlFlowProcessor] " + element.toString());
             }
         };
@@ -141,7 +141,7 @@ public class JetControlFlowProcessor {
         }
 
         @Override
-        public void visitParenthesizedExpression(JetParenthesizedExpression expression) {
+        public void visitParenthesizedExpression(@NotNull JetParenthesizedExpression expression) {
             builder.read(expression);
 
             JetExpression innerExpression = expression.getExpression();
@@ -151,7 +151,7 @@ public class JetControlFlowProcessor {
         }
 
         @Override
-        public void visitAnnotatedExpression(JetAnnotatedExpression expression) {
+        public void visitAnnotatedExpression(@NotNull JetAnnotatedExpression expression) {
             builder.read(expression);
 
             JetExpression baseExpression = expression.getBaseExpression();
@@ -161,17 +161,17 @@ public class JetControlFlowProcessor {
         }
 
         @Override
-        public void visitThisExpression(JetThisExpression expression) {
+        public void visitThisExpression(@NotNull JetThisExpression expression) {
             builder.read(expression);
         }
 
         @Override
-        public void visitConstantExpression(JetConstantExpression expression) {
+        public void visitConstantExpression(@NotNull JetConstantExpression expression) {
             builder.read(expression);
         }
 
         @Override
-        public void visitSimpleNameExpression(JetSimpleNameExpression expression) {
+        public void visitSimpleNameExpression(@NotNull JetSimpleNameExpression expression) {
             builder.read(expression);
             if (trace.get(BindingContext.PROCESSED, expression)) {
                 JetType type = trace.getBindingContext().get(BindingContext.EXPRESSION_TYPE, expression);
@@ -182,7 +182,7 @@ public class JetControlFlowProcessor {
         }
 
         @Override
-        public void visitLabelQualifiedExpression(JetLabelQualifiedExpression expression) {
+        public void visitLabelQualifiedExpression(@NotNull JetLabelQualifiedExpression expression) {
             String labelName = expression.getLabelName();
             JetExpression labeledExpression = expression.getLabeledExpression();
             if (labelName != null && labeledExpression != null) {
@@ -198,7 +198,7 @@ public class JetControlFlowProcessor {
         }
 
         @SuppressWarnings("SuspiciousMethodCalls") @Override
-        public void visitBinaryExpression(JetBinaryExpression expression) {
+        public void visitBinaryExpression(@NotNull JetBinaryExpression expression) {
             IElementType operationType = expression.getOperationReference().getReferencedNameElementType();
             JetExpression right = expression.getRight();
             if (operationType == JetTokens.ANDAND) {
@@ -294,7 +294,7 @@ public class JetControlFlowProcessor {
         }
 
         @Override
-        public void visitUnaryExpression(JetUnaryExpression expression) {
+        public void visitUnaryExpression(@NotNull JetUnaryExpression expression) {
             JetSimpleNameExpression operationSign = expression.getOperationReference();
             IElementType operationType = operationSign.getReferencedNameElementType();
             JetExpression baseExpression = expression.getBaseExpression();
@@ -322,7 +322,7 @@ public class JetControlFlowProcessor {
 
 
         @Override
-        public void visitIfExpression(JetIfExpression expression) {
+        public void visitIfExpression(@NotNull JetIfExpression expression) {
             JetExpression condition = expression.getCondition();
             if (condition != null) {
                 generateInstructions(condition, true);
@@ -376,7 +376,7 @@ public class JetControlFlowProcessor {
        
 
         @Override
-        public void visitTryExpression(JetTryExpression expression) {
+        public void visitTryExpression(@NotNull JetTryExpression expression) {
             builder.read(expression);
             JetFinallySection finallyBlock = expression.getFinallyBlock();
             final FinallyBlockGenerator finallyBlockGenerator = new FinallyBlockGenerator(finallyBlock);
@@ -461,7 +461,7 @@ public class JetControlFlowProcessor {
         }
 
         @Override
-        public void visitWhileExpression(JetWhileExpression expression) {
+        public void visitWhileExpression(@NotNull JetWhileExpression expression) {
             builder.read(expression);
             LoopInfo loopInfo = builder.enterLoop(expression, null, null);
 
@@ -492,7 +492,7 @@ public class JetControlFlowProcessor {
         }
 
         @Override
-        public void visitDoWhileExpression(JetDoWhileExpression expression) {
+        public void visitDoWhileExpression(@NotNull JetDoWhileExpression expression) {
             builder.read(expression);
             LoopInfo loopInfo = builder.enterLoop(expression, null, null);
 
@@ -512,7 +512,7 @@ public class JetControlFlowProcessor {
         }
 
         @Override
-        public void visitForExpression(JetForExpression expression) {
+        public void visitForExpression(@NotNull JetForExpression expression) {
             builder.read(expression);
             JetExpression loopRange = expression.getLoopRange();
             if (loopRange != null) {
@@ -548,7 +548,7 @@ public class JetControlFlowProcessor {
         }
 
         @Override
-        public void visitBreakExpression(JetBreakExpression expression) {
+        public void visitBreakExpression(@NotNull JetBreakExpression expression) {
             JetElement loop = getCorrespondingLoop(expression);
             if (loop != null) {
                 builder.jump(builder.getExitPoint(loop));
@@ -556,7 +556,7 @@ public class JetControlFlowProcessor {
         }
 
         @Override
-        public void visitContinueExpression(JetContinueExpression expression) {
+        public void visitContinueExpression(@NotNull JetContinueExpression expression) {
             JetElement loop = getCorrespondingLoop(expression);
             if (loop != null) {
                 builder.jump(builder.getEntryPoint(loop));
@@ -588,7 +588,7 @@ public class JetControlFlowProcessor {
         }
 
         @Override
-        public void visitReturnExpression(JetReturnExpression expression) {
+        public void visitReturnExpression(@NotNull JetReturnExpression expression) {
             JetExpression returnedExpression = expression.getReturnedExpression();
             if (returnedExpression != null) {
                 generateInstructions(returnedExpression, false);
@@ -623,7 +623,7 @@ public class JetControlFlowProcessor {
         }
 
         @Override
-        public void visitParameter(JetParameter parameter) {
+        public void visitParameter(@NotNull JetParameter parameter) {
             builder.declare(parameter);
             JetExpression defaultValue = parameter.getDefaultValue();
             if (defaultValue != null) {
@@ -633,7 +633,7 @@ public class JetControlFlowProcessor {
         }
 
         @Override
-        public void visitBlockExpression(JetBlockExpression expression) {
+        public void visitBlockExpression(@NotNull JetBlockExpression expression) {
             List<JetElement> statements = expression.getStatements();
             for (JetElement statement : statements) {
                 generateInstructions(statement, false);
@@ -644,19 +644,19 @@ public class JetControlFlowProcessor {
         }
 
         @Override
-        public void visitNamedFunction(JetNamedFunction function) {
+        public void visitNamedFunction(@NotNull JetNamedFunction function) {
             processLocalDeclaration(function);
         }
 
         @Override
-        public void visitFunctionLiteralExpression(JetFunctionLiteralExpression expression) {
+        public void visitFunctionLiteralExpression(@NotNull JetFunctionLiteralExpression expression) {
             JetFunctionLiteral functionLiteral = expression.getFunctionLiteral();
             processLocalDeclaration(functionLiteral);
             builder.read(expression);
         }
 
         @Override
-        public void visitQualifiedExpression(JetQualifiedExpression expression) {
+        public void visitQualifiedExpression(@NotNull JetQualifiedExpression expression) {
             generateInstructions(expression.getReceiverExpression(), false);
             JetExpression selectorExpression = expression.getSelectorExpression();
             if (selectorExpression != null) {
@@ -685,7 +685,7 @@ public class JetControlFlowProcessor {
         }
 
         @Override
-        public void visitCallExpression(JetCallExpression expression) {
+        public void visitCallExpression(@NotNull JetCallExpression expression) {
             //inline functions after M1
 //            ResolvedCall<? extends CallableDescriptor> resolvedCall = trace.get(BindingContext.RESOLVED_CALL, expression.getCalleeExpression());
 //            assert resolvedCall != null;
@@ -722,7 +722,7 @@ public class JetControlFlowProcessor {
 //        }
 
         @Override
-        public void visitProperty(JetProperty property) {
+        public void visitProperty(@NotNull JetProperty property) {
             builder.declare(property);
             JetExpression initializer = property.getInitializer();
             if (initializer != null) {
@@ -739,7 +739,7 @@ public class JetControlFlowProcessor {
         }
 
         @Override
-        public void visitMultiDeclaration(JetMultiDeclaration declaration) {
+        public void visitMultiDeclaration(@NotNull JetMultiDeclaration declaration) {
             JetExpression initializer = declaration.getInitializer();
             if (initializer != null) {
                 generateInstructions(initializer, false);
@@ -752,12 +752,12 @@ public class JetControlFlowProcessor {
         }
 
         @Override
-        public void visitPropertyAccessor(JetPropertyAccessor accessor) {
+        public void visitPropertyAccessor(@NotNull JetPropertyAccessor accessor) {
             processLocalDeclaration(accessor);
         }
 
         @Override
-        public void visitBinaryWithTypeRHSExpression(JetBinaryExpressionWithTypeRHS expression) {
+        public void visitBinaryWithTypeRHSExpression(@NotNull JetBinaryExpressionWithTypeRHS expression) {
             IElementType operationType = expression.getOperationReference().getReferencedNameElementType();
             if (operationType == JetTokens.COLON || operationType == JetTokens.AS_KEYWORD || operationType == JetTokens.AS_SAFE) {
                 generateInstructions(expression.getLeft(), false);
@@ -769,7 +769,7 @@ public class JetControlFlowProcessor {
         }
 
         @Override
-        public void visitThrowExpression(JetThrowExpression expression) {
+        public void visitThrowExpression(@NotNull JetThrowExpression expression) {
             JetExpression thrownExpression = expression.getThrownExpression();
             if (thrownExpression != null) {
                 generateInstructions(thrownExpression, false);
@@ -778,7 +778,7 @@ public class JetControlFlowProcessor {
         }
 
         @Override
-        public void visitArrayAccessExpression(JetArrayAccessExpression expression) {
+        public void visitArrayAccessExpression(@NotNull JetArrayAccessExpression expression) {
             for (JetExpression index : expression.getIndexExpressions()) {
                 generateInstructions(index, false);
             }
@@ -788,7 +788,7 @@ public class JetControlFlowProcessor {
         }
 
         @Override
-        public void visitIsExpression(JetIsExpression expression) {
+        public void visitIsExpression(@NotNull JetIsExpression expression) {
             generateInstructions(expression.getLeftHandSide(), inCondition);
             // no CF for types
             // TODO : builder.read(expression.getPattern());
@@ -796,7 +796,7 @@ public class JetControlFlowProcessor {
         }
 
         @Override
-        public void visitWhenExpression(JetWhenExpression expression) {
+        public void visitWhenExpression(@NotNull JetWhenExpression expression) {
             JetExpression subjectExpression = expression.getSubjectExpression();
             if (subjectExpression != null) {
                 generateInstructions(subjectExpression, inCondition);
@@ -853,7 +853,7 @@ public class JetControlFlowProcessor {
         }
 
         @Override
-        public void visitObjectLiteralExpression(JetObjectLiteralExpression expression) {
+        public void visitObjectLiteralExpression(@NotNull JetObjectLiteralExpression expression) {
             JetObjectDeclaration declaration = expression.getObjectDeclaration();
             generateInstructions(declaration, inCondition);
 
@@ -871,12 +871,12 @@ public class JetControlFlowProcessor {
         }
 
         @Override
-        public void visitObjectDeclaration(JetObjectDeclaration objectDeclaration) {
+        public void visitObjectDeclaration(@NotNull JetObjectDeclaration objectDeclaration) {
             visitClassOrObject(objectDeclaration);
         }
 
         @Override
-        public void visitStringTemplateExpression(JetStringTemplateExpression expression) {
+        public void visitStringTemplateExpression(@NotNull JetStringTemplateExpression expression) {
             for (JetStringTemplateEntry entry : expression.getEntries()) {
                 if (entry instanceof JetStringTemplateEntryWithExpression) {
                     JetStringTemplateEntryWithExpression entryWithExpression = (JetStringTemplateEntryWithExpression) entry;
@@ -887,12 +887,12 @@ public class JetControlFlowProcessor {
         }
 
         @Override
-        public void visitTypeProjection(JetTypeProjection typeProjection) {
+        public void visitTypeProjection(@NotNull JetTypeProjection typeProjection) {
             // TODO : Support Type Arguments. Class object may be initialized at this point");
         }
 
         @Override
-        public void visitAnonymousInitializer(JetClassInitializer classInitializer) {
+        public void visitAnonymousInitializer(@NotNull JetClassInitializer classInitializer) {
             generateInstructions(classInitializer.getBody(), inCondition);
         }
 
@@ -909,7 +909,7 @@ public class JetControlFlowProcessor {
         }
 
         @Override
-        public void visitClass(JetClass klass) {
+        public void visitClass(@NotNull JetClass klass) {
             List<JetParameter> parameters = klass.getPrimaryConstructorParameters();
             for (JetParameter parameter : parameters) {
                 generateInstructions(parameter, inCondition);
@@ -918,7 +918,7 @@ public class JetControlFlowProcessor {
         }
 
         @Override
-        public void visitDelegationToSuperCallSpecifier(JetDelegatorToSuperCall call) {
+        public void visitDelegationToSuperCallSpecifier(@NotNull JetDelegatorToSuperCall call) {
             List<? extends ValueArgument> valueArguments = call.getValueArguments();
             for (ValueArgument valueArgument : valueArguments) {
                 generateInstructions(valueArgument.getArgumentExpression(), inCondition);
@@ -926,12 +926,12 @@ public class JetControlFlowProcessor {
         }
 
         @Override
-        public void visitDelegationByExpressionSpecifier(JetDelegatorByExpressionSpecifier specifier) {
+        public void visitDelegationByExpressionSpecifier(@NotNull JetDelegatorByExpressionSpecifier specifier) {
             generateInstructions(specifier.getDelegateExpression(), inCondition);
         }
 
         @Override
-        public void visitJetFile(JetFile file) {
+        public void visitJetFile(@NotNull JetFile file) {
             for (JetDeclaration declaration : file.getDeclarations()) {
                 if (declaration instanceof JetProperty) {
                     generateInstructions(declaration, inCondition);
@@ -940,7 +940,7 @@ public class JetControlFlowProcessor {
         }
 
         @Override
-        public void visitJetElement(JetElement element) {
+        public void visitJetElement(@NotNull JetElement element) {
             builder.unsupported(element);
         }
     }
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/JetFlowInformationProvider.java b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/JetFlowInformationProvider.java
index 96a26fd797e..16382f46f48 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/cfg/JetFlowInformationProvider.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/cfg/JetFlowInformationProvider.java
@@ -144,14 +144,14 @@ public class JetFlowInformationProvider {
         for (JetElement returnedExpression : returnedExpressions) {
             returnedExpression.accept(new JetVisitorVoid() {
                 @Override
-                public void visitReturnExpression(JetReturnExpression expression) {
+                public void visitReturnExpression(@NotNull JetReturnExpression expression) {
                     if (!blockBody) {
                         trace.report(RETURN_IN_FUNCTION_WITH_EXPRESSION_BODY.on(expression));
                     }
                 }
 
                 @Override
-                public void visitExpression(JetExpression expression) {
+                public void visitExpression(@NotNull JetExpression expression) {
                     if (blockBody && !noExpectedType(expectedReturnType) && !KotlinBuiltIns.getInstance().isUnit(expectedReturnType) && !rootUnreachableElements.contains(expression)) {
                         noReturnError[0] = true;
                     }
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/psi/JetPsiUtil.java b/compiler/frontend/src/org/jetbrains/jet/lang/psi/JetPsiUtil.java
index fc7774462e2..7c9730f6397 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/psi/JetPsiUtil.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/psi/JetPsiUtil.java
@@ -138,7 +138,7 @@ public class JetPsiUtil {
         final Set<JetElement> shadowedElements = new HashSet<JetElement>();
         JetVisitorVoid shadowAllChildren = new JetVisitorVoid() {
             @Override
-            public void visitJetElement(JetElement element) {
+            public void visitJetElement(@NotNull JetElement element) {
                 if (shadowedElements.add(element)) {
                     element.acceptChildren(this);
                 }
@@ -841,7 +841,7 @@ public class JetPsiUtil {
         ((JetElement) root).accept(
                 new JetVisitorVoid() {
                     @Override
-                    public void visitJetElement(JetElement element) {
+                    public void visitJetElement(@NotNull JetElement element) {
                         if (predicate.apply(element)) {
                             //noinspection unchecked
                             results.add(element);
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/psi/JetVisitorVoid.java b/compiler/frontend/src/org/jetbrains/jet/lang/psi/JetVisitorVoid.java
index ff0be8afff0..a7985b62e30 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/psi/JetVisitorVoid.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/psi/JetVisitorVoid.java
@@ -17,161 +17,162 @@
 package org.jetbrains.jet.lang.psi;
 
 import com.intellij.psi.PsiElementVisitor;
+import org.jetbrains.annotations.NotNull;
 
 public class JetVisitorVoid extends PsiElementVisitor {
-    public void visitJetElement(JetElement element) {
+    public void visitJetElement(@NotNull JetElement element) {
         visitElement(element);
     }
 
-    public void visitDeclaration(JetDeclaration dcl) {
+    public void visitDeclaration(@NotNull JetDeclaration dcl) {
         visitExpression(dcl);
     }
 
-    public void visitClass(JetClass klass) {
+    public void visitClass(@NotNull JetClass klass) {
         visitNamedDeclaration(klass);
     }
 
-    public void visitClassObject(JetClassObject classObject) {
+    public void visitClassObject(@NotNull JetClassObject classObject) {
         visitDeclaration(classObject);
     }
 
-    public void visitNamedFunction(JetNamedFunction function) {
+    public void visitNamedFunction(@NotNull JetNamedFunction function) {
         visitNamedDeclaration(function);
     }
 
-    public void visitProperty(JetProperty property) {
+    public void visitProperty(@NotNull JetProperty property) {
         visitNamedDeclaration(property);
     }
 
-    public void visitTypedef(JetTypedef typedef) {
+    public void visitTypedef(@NotNull JetTypedef typedef) {
         visitNamedDeclaration(typedef);
     }
 
-    public void visitJetFile(JetFile file) {
+    public void visitJetFile(@NotNull JetFile file) {
         visitFile(file);
     }
 
-    public void visitScript(JetScript script) {
+    public void visitScript(@NotNull JetScript script) {
         visitDeclaration(script);
     }
 
-    public void visitImportDirective(JetImportDirective importDirective) {
+    public void visitImportDirective(@NotNull JetImportDirective importDirective) {
         visitJetElement(importDirective);
     }
 
-    public void visitImportList(JetImportList importList) {
+    public void visitImportList(@NotNull JetImportList importList) {
         visitJetElement(importList);
     }
 
-    public void visitClassBody(JetClassBody classBody) {
+    public void visitClassBody(@NotNull JetClassBody classBody) {
         visitJetElement(classBody);
     }
 
-    public void visitModifierList(JetModifierList list) {
+    public void visitModifierList(@NotNull JetModifierList list) {
         visitJetElement(list);
     }
 
-    public void visitAnnotation(JetAnnotation annotation) {
+    public void visitAnnotation(@NotNull JetAnnotation annotation) {
         visitJetElement(annotation);
     }
 
-    public void visitAnnotationEntry(JetAnnotationEntry annotationEntry) {
+    public void visitAnnotationEntry(@NotNull JetAnnotationEntry annotationEntry) {
         visitJetElement(annotationEntry);
     }
 
-    public void visitTypeParameterList(JetTypeParameterList list) {
+    public void visitTypeParameterList(@NotNull JetTypeParameterList list) {
         visitJetElement(list);
     }
 
-    public void visitTypeParameter(JetTypeParameter parameter) {
+    public void visitTypeParameter(@NotNull JetTypeParameter parameter) {
         visitNamedDeclaration(parameter);
     }
 
-    public void visitEnumEntry(JetEnumEntry enumEntry) {
+    public void visitEnumEntry(@NotNull JetEnumEntry enumEntry) {
         visitClass(enumEntry);
     }
 
-    public void visitParameterList(JetParameterList list) {
+    public void visitParameterList(@NotNull JetParameterList list) {
         visitJetElement(list);
     }
 
-    public void visitParameter(JetParameter parameter) {
+    public void visitParameter(@NotNull JetParameter parameter) {
         visitNamedDeclaration(parameter);
     }
 
-    public void visitDelegationSpecifierList(JetDelegationSpecifierList list) {
+    public void visitDelegationSpecifierList(@NotNull JetDelegationSpecifierList list) {
         visitJetElement(list);
     }
 
-    public void visitDelegationSpecifier(JetDelegationSpecifier specifier) {
+    public void visitDelegationSpecifier(@NotNull JetDelegationSpecifier specifier) {
         visitJetElement(specifier);
     }
 
-    public void visitDelegationByExpressionSpecifier(JetDelegatorByExpressionSpecifier specifier) {
+    public void visitDelegationByExpressionSpecifier(@NotNull JetDelegatorByExpressionSpecifier specifier) {
         visitDelegationSpecifier(specifier);
     }
 
-    public void visitDelegationToSuperCallSpecifier(JetDelegatorToSuperCall call) {
+    public void visitDelegationToSuperCallSpecifier(@NotNull JetDelegatorToSuperCall call) {
         visitDelegationSpecifier(call);
     }
 
-    public void visitDelegationToSuperClassSpecifier(JetDelegatorToSuperClass specifier) {
+    public void visitDelegationToSuperClassSpecifier(@NotNull JetDelegatorToSuperClass specifier) {
         visitDelegationSpecifier(specifier);
     }
 
-    public void visitDelegationToThisCall(JetDelegatorToThisCall thisCall) {
+    public void visitDelegationToThisCall(@NotNull JetDelegatorToThisCall thisCall) {
         visitDelegationSpecifier(thisCall);
     }
 
-    public void visitPropertyDelegate(JetPropertyDelegate delegate) {
+    public void visitPropertyDelegate(@NotNull JetPropertyDelegate delegate) {
         visitJetElement(delegate);
     }
 
-    public void visitTypeReference(JetTypeReference typeReference) {
+    public void visitTypeReference(@NotNull JetTypeReference typeReference) {
         visitJetElement(typeReference);
     }
 
-    public void visitValueArgumentList(JetValueArgumentList list) {
+    public void visitValueArgumentList(@NotNull JetValueArgumentList list) {
         visitJetElement(list);
     }
 
-    public void visitArgument(JetValueArgument argument) {
+    public void visitArgument(@NotNull JetValueArgument argument) {
         visitJetElement(argument);
     }
 
-    public void visitExpression(JetExpression expression) {
+    public void visitExpression(@NotNull JetExpression expression) {
         visitJetElement(expression);
     }
 
-    public void visitLoopExpression(JetLoopExpression loopExpression) {
+    public void visitLoopExpression(@NotNull JetLoopExpression loopExpression) {
         visitExpression(loopExpression);
     }
 
-    public void visitConstantExpression(JetConstantExpression expression) {
+    public void visitConstantExpression(@NotNull JetConstantExpression expression) {
         visitExpression(expression);
     }
 
-    public void visitSimpleNameExpression(JetSimpleNameExpression expression) {
+    public void visitSimpleNameExpression(@NotNull JetSimpleNameExpression expression) {
         visitReferenceExpression(expression);
     }
 
-    public void visitReferenceExpression(JetReferenceExpression expression) {
+    public void visitReferenceExpression(@NotNull JetReferenceExpression expression) {
         visitExpression(expression);
     }
 
-    public void visitPrefixExpression(JetPrefixExpression expression) {
+    public void visitPrefixExpression(@NotNull JetPrefixExpression expression) {
         visitUnaryExpression(expression);
     }
 
-    public void visitPostfixExpression(JetPostfixExpression expression) {
+    public void visitPostfixExpression(@NotNull JetPostfixExpression expression) {
         visitUnaryExpression(expression);
     }
 
-    public void visitUnaryExpression(JetUnaryExpression expression) {
+    public void visitUnaryExpression(@NotNull JetUnaryExpression expression) {
         visitExpression(expression);
     }
 
-    public void visitBinaryExpression(JetBinaryExpression expression) {
+    public void visitBinaryExpression(@NotNull JetBinaryExpression expression) {
         visitExpression(expression);
     }
 
@@ -179,231 +180,231 @@ public class JetVisitorVoid extends PsiElementVisitor {
 //        visitExpression(expression);
 //    }
 //
-    public void visitReturnExpression(JetReturnExpression expression) {
+    public void visitReturnExpression(@NotNull JetReturnExpression expression) {
         visitLabelQualifiedExpression(expression);
     }
 
-    public void visitLabelQualifiedExpression(JetLabelQualifiedExpression expression) {
+    public void visitLabelQualifiedExpression(@NotNull JetLabelQualifiedExpression expression) {
         visitExpression(expression);
     }
 
-    public void visitThrowExpression(JetThrowExpression expression) {
+    public void visitThrowExpression(@NotNull JetThrowExpression expression) {
         visitExpression(expression);
     }
 
-    public void visitBreakExpression(JetBreakExpression expression) {
+    public void visitBreakExpression(@NotNull JetBreakExpression expression) {
         visitLabelQualifiedExpression(expression);
     }
 
-    public void visitContinueExpression(JetContinueExpression expression) {
+    public void visitContinueExpression(@NotNull JetContinueExpression expression) {
         visitLabelQualifiedExpression(expression);
     }
 
-    public void visitIfExpression(JetIfExpression expression) {
+    public void visitIfExpression(@NotNull JetIfExpression expression) {
         visitExpression(expression);
     }
 
-    public void visitWhenExpression(JetWhenExpression expression) {
+    public void visitWhenExpression(@NotNull JetWhenExpression expression) {
         visitExpression(expression);
     }
 
-    public void visitTryExpression(JetTryExpression expression) {
+    public void visitTryExpression(@NotNull JetTryExpression expression) {
         visitExpression(expression);
     }
 
-    public void visitForExpression(JetForExpression expression) {
+    public void visitForExpression(@NotNull JetForExpression expression) {
         visitLoopExpression(expression);
     }
 
-    public void visitWhileExpression(JetWhileExpression expression) {
+    public void visitWhileExpression(@NotNull JetWhileExpression expression) {
         visitLoopExpression(expression);
     }
 
-    public void visitDoWhileExpression(JetDoWhileExpression expression) {
+    public void visitDoWhileExpression(@NotNull JetDoWhileExpression expression) {
         visitLoopExpression(expression);
     }
 
-    public void visitFunctionLiteralExpression(JetFunctionLiteralExpression expression) {
+    public void visitFunctionLiteralExpression(@NotNull JetFunctionLiteralExpression expression) {
         visitExpression(expression);
     }
 
-    public void visitAnnotatedExpression(JetAnnotatedExpression expression) {
+    public void visitAnnotatedExpression(@NotNull JetAnnotatedExpression expression) {
         visitExpression(expression);
     }
 
-    public void visitCallExpression(JetCallExpression expression) {
+    public void visitCallExpression(@NotNull JetCallExpression expression) {
         visitReferenceExpression(expression);
     }
 
-    public void visitArrayAccessExpression(JetArrayAccessExpression expression) {
+    public void visitArrayAccessExpression(@NotNull JetArrayAccessExpression expression) {
         visitReferenceExpression(expression);
     }
 
-    public void visitQualifiedExpression(JetQualifiedExpression expression) {
+    public void visitQualifiedExpression(@NotNull JetQualifiedExpression expression) {
         visitExpression(expression);
     }
 
-    public void visitCallableReferenceExpression(JetCallableReferenceExpression expression) {
+    public void visitCallableReferenceExpression(@NotNull JetCallableReferenceExpression expression) {
         visitExpression(expression);
     }
 
-    public void visitDotQualifiedExpression(JetDotQualifiedExpression expression) {
+    public void visitDotQualifiedExpression(@NotNull JetDotQualifiedExpression expression) {
         visitQualifiedExpression(expression);
     }
 
-    public void visitSafeQualifiedExpression(JetSafeQualifiedExpression expression) {
+    public void visitSafeQualifiedExpression(@NotNull JetSafeQualifiedExpression expression) {
         visitQualifiedExpression(expression);
     }
 
-    public void visitObjectLiteralExpression(JetObjectLiteralExpression expression) {
+    public void visitObjectLiteralExpression(@NotNull JetObjectLiteralExpression expression) {
         visitExpression(expression);
     }
 
-    public void visitRootNamespaceExpression(JetRootNamespaceExpression expression) {
+    public void visitRootNamespaceExpression(@NotNull JetRootNamespaceExpression expression) {
         visitExpression(expression);
     }
 
-    public void visitBlockExpression(JetBlockExpression expression) {
+    public void visitBlockExpression(@NotNull JetBlockExpression expression) {
         visitExpression(expression);
     }
 
-    public void visitCatchSection(JetCatchClause catchClause) {
+    public void visitCatchSection(@NotNull JetCatchClause catchClause) {
         visitJetElement(catchClause);
     }
 
-    public void visitFinallySection(JetFinallySection finallySection) {
+    public void visitFinallySection(@NotNull JetFinallySection finallySection) {
         visitJetElement(finallySection);
     }
 
-    public void visitTypeArgumentList(JetTypeArgumentList typeArgumentList) {
+    public void visitTypeArgumentList(@NotNull JetTypeArgumentList typeArgumentList) {
         visitJetElement(typeArgumentList);
     }
 
-    public void visitThisExpression(JetThisExpression expression) {
+    public void visitThisExpression(@NotNull JetThisExpression expression) {
         visitLabelQualifiedExpression(expression);
     }
 
-    public void visitSuperExpression(JetSuperExpression expression) {
+    public void visitSuperExpression(@NotNull JetSuperExpression expression) {
         visitLabelQualifiedExpression(expression);
     }
 
-    public void visitParenthesizedExpression(JetParenthesizedExpression expression) {
+    public void visitParenthesizedExpression(@NotNull JetParenthesizedExpression expression) {
         visitExpression(expression);
     }
 
-    public void visitInitializerList(JetInitializerList list) {
+    public void visitInitializerList(@NotNull JetInitializerList list) {
         visitJetElement(list);
     }
 
-    public void visitAnonymousInitializer(JetClassInitializer initializer) {
+    public void visitAnonymousInitializer(@NotNull JetClassInitializer initializer) {
         visitDeclaration(initializer);
     }
 
-    public void visitPropertyAccessor(JetPropertyAccessor accessor) {
+    public void visitPropertyAccessor(@NotNull JetPropertyAccessor accessor) {
         visitDeclaration(accessor);
     }
 
-    public void visitTypeConstraintList(JetTypeConstraintList list) {
+    public void visitTypeConstraintList(@NotNull JetTypeConstraintList list) {
         visitJetElement(list);
     }
 
-    public void visitTypeConstraint(JetTypeConstraint constraint) {
+    public void visitTypeConstraint(@NotNull JetTypeConstraint constraint) {
         visitJetElement(constraint);
     }
 
-    private void visitTypeElement(JetTypeElement type) {
+    private void visitTypeElement(@NotNull JetTypeElement type) {
         visitJetElement(type);
     }
 
-    public void visitUserType(JetUserType type) {
+    public void visitUserType(@NotNull JetUserType type) {
         visitTypeElement(type);
     }
 
-    public void visitFunctionType(JetFunctionType type) {
+    public void visitFunctionType(@NotNull JetFunctionType type) {
         visitTypeElement(type);
     }
 
-    public void visitSelfType(JetSelfType type) {
+    public void visitSelfType(@NotNull JetSelfType type) {
         visitTypeElement(type);
     }
 
-    public void visitBinaryWithTypeRHSExpression(JetBinaryExpressionWithTypeRHS expression) {
+    public void visitBinaryWithTypeRHSExpression(@NotNull JetBinaryExpressionWithTypeRHS expression) {
         visitExpression(expression);
     }
 
-    public void visitStringTemplateExpression(JetStringTemplateExpression expression) {
+    public void visitStringTemplateExpression(@NotNull JetStringTemplateExpression expression) {
         visitExpression(expression);
     }
 
-    public void visitNamedDeclaration(JetNamedDeclaration declaration) {
+    public void visitNamedDeclaration(@NotNull JetNamedDeclaration declaration) {
         visitDeclaration(declaration);
     }
 
-    public void visitNullableType(JetNullableType nullableType) {
+    public void visitNullableType(@NotNull JetNullableType nullableType) {
         visitTypeElement(nullableType);
     }
 
-    public void visitTypeProjection(JetTypeProjection typeProjection) {
+    public void visitTypeProjection(@NotNull JetTypeProjection typeProjection) {
         visitJetElement(typeProjection);
     }
 
-    public void visitWhenEntry(JetWhenEntry jetWhenEntry) {
+    public void visitWhenEntry(@NotNull JetWhenEntry jetWhenEntry) {
         visitJetElement(jetWhenEntry);
     }
 
-    public void visitIsExpression(JetIsExpression expression) {
+    public void visitIsExpression(@NotNull JetIsExpression expression) {
         visitExpression(expression);
     }
 
-    public void visitWhenConditionIsPattern(JetWhenConditionIsPattern condition) {
+    public void visitWhenConditionIsPattern(@NotNull JetWhenConditionIsPattern condition) {
         visitJetElement(condition);
     }
 
-    public void visitWhenConditionInRange(JetWhenConditionInRange condition) {
+    public void visitWhenConditionInRange(@NotNull JetWhenConditionInRange condition) {
         visitJetElement(condition);
     }
 
-    public void visitWhenConditionWithExpression(JetWhenConditionWithExpression condition) {
+    public void visitWhenConditionWithExpression(@NotNull JetWhenConditionWithExpression condition) {
         visitJetElement(condition);
     }
 
-    public void visitObjectDeclaration(JetObjectDeclaration declaration) {
+    public void visitObjectDeclaration(@NotNull JetObjectDeclaration declaration) {
         visitNamedDeclaration(declaration);
     }
 
-    public void visitObjectDeclarationName(JetObjectDeclarationName declaration) {
+    public void visitObjectDeclarationName(@NotNull JetObjectDeclarationName declaration) {
         visitNamedDeclaration(declaration);
     }
 
-    public void visitStringTemplateEntry(JetStringTemplateEntry entry) {
+    public void visitStringTemplateEntry(@NotNull JetStringTemplateEntry entry) {
         visitJetElement(entry);
     }
 
-    public void visitStringTemplateEntryWithExpression(JetStringTemplateEntryWithExpression entry) {
+    public void visitStringTemplateEntryWithExpression(@NotNull JetStringTemplateEntryWithExpression entry) {
         visitStringTemplateEntry(entry);
     }
 
-    public void visitBlockStringTemplateEntry(JetBlockStringTemplateEntry entry) {
+    public void visitBlockStringTemplateEntry(@NotNull JetBlockStringTemplateEntry entry) {
         visitStringTemplateEntryWithExpression(entry);
     }
 
-    public void visitSimpleNameStringTemplateEntry(JetSimpleNameStringTemplateEntry entry) {
+    public void visitSimpleNameStringTemplateEntry(@NotNull JetSimpleNameStringTemplateEntry entry) {
         visitStringTemplateEntryWithExpression(entry);
     }
 
-    public void visitLiteralStringTemplateEntry(JetLiteralStringTemplateEntry entry) {
+    public void visitLiteralStringTemplateEntry(@NotNull JetLiteralStringTemplateEntry entry) {
         visitStringTemplateEntry(entry);
     }
 
-    public void visitEscapeStringTemplateEntry(JetEscapeStringTemplateEntry entry) {
+    public void visitEscapeStringTemplateEntry(@NotNull JetEscapeStringTemplateEntry entry) {
         visitStringTemplateEntry(entry);
     }
 
-    public void visitMultiDeclaration(JetMultiDeclaration declaration) {
+    public void visitMultiDeclaration(@NotNull JetMultiDeclaration declaration) {
         visitDeclaration(declaration);
     }
 
-    public void visitMultiDeclarationEntry(JetMultiDeclarationEntry entry) {
+    public void visitMultiDeclarationEntry(@NotNull JetMultiDeclarationEntry entry) {
         visitNamedDeclaration(entry);
     }
 }
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/BodyResolver.java b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/BodyResolver.java
index 0215f6bed3e..7a09e527634 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/BodyResolver.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/BodyResolver.java
@@ -193,7 +193,7 @@ public class BodyResolver {
             }
 
             @Override
-            public void visitDelegationByExpressionSpecifier(JetDelegatorByExpressionSpecifier specifier) {
+            public void visitDelegationByExpressionSpecifier(@NotNull JetDelegatorByExpressionSpecifier specifier) {
                 if (descriptor.getKind() == ClassKind.TRAIT) {
                     trace.report(DELEGATION_IN_TRAIT.on(specifier));
                 }
@@ -224,7 +224,7 @@ public class BodyResolver {
             }
 
             @Override
-            public void visitDelegationToSuperCallSpecifier(JetDelegatorToSuperCall call) {
+            public void visitDelegationToSuperCallSpecifier(@NotNull JetDelegatorToSuperCall call) {
                 JetValueArgumentList valueArgumentList = call.getValueArgumentList();
                 PsiElement elementToMark = valueArgumentList == null ? call : valueArgumentList;
                 if (descriptor.getKind() == ClassKind.TRAIT) {
@@ -256,7 +256,7 @@ public class BodyResolver {
             }
 
             @Override
-            public void visitDelegationToSuperClassSpecifier(JetDelegatorToSuperClass specifier) {
+            public void visitDelegationToSuperClassSpecifier(@NotNull JetDelegatorToSuperClass specifier) {
                 JetTypeReference typeReference = specifier.getTypeReference();
                 JetType supertype = trace.getBindingContext().get(BindingContext.TYPE, typeReference);
                 recordSupertype(typeReference, supertype);
@@ -270,12 +270,12 @@ public class BodyResolver {
             }
 
             @Override
-            public void visitDelegationToThisCall(JetDelegatorToThisCall thisCall) {
+            public void visitDelegationToThisCall(@NotNull JetDelegatorToThisCall thisCall) {
                 throw new IllegalStateException("This-calls should be prohibited by the parser");
             }
 
             @Override
-            public void visitJetElement(JetElement element) {
+            public void visitJetElement(@NotNull JetElement element) {
                 throw new UnsupportedOperationException(element.getText() + " : " + element);
             }
         };
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/DeclarationResolver.java b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/DeclarationResolver.java
index b011341e4fa..d47d8f6c9ab 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/DeclarationResolver.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/DeclarationResolver.java
@@ -217,7 +217,7 @@ public class DeclarationResolver {
         for (JetDeclaration declaration : declarations) {
             declaration.accept(new JetVisitorVoid() {
                 @Override
-                public void visitNamedFunction(JetNamedFunction function) {
+                public void visitNamedFunction(@NotNull JetNamedFunction function) {
                     SimpleFunctionDescriptor functionDescriptor = descriptorResolver.resolveFunctionDescriptor(
                             namespaceLike.getOwnerForChildren(),
                             scopeForFunctions,
@@ -231,7 +231,7 @@ public class DeclarationResolver {
                 }
 
                 @Override
-                public void visitProperty(JetProperty property) {
+                public void visitProperty(@NotNull JetProperty property) {
                     PropertyDescriptor propertyDescriptor = descriptorResolver.resolvePropertyDescriptor(
                             namespaceLike.getOwnerForChildren(),
                             scopeForPropertyInitializers,
@@ -252,7 +252,7 @@ public class DeclarationResolver {
                 }
 
                 @Override
-                public void visitObjectDeclaration(JetObjectDeclaration declaration) {
+                public void visitObjectDeclaration(@NotNull JetObjectDeclaration declaration) {
                     PropertyDescriptor propertyDescriptor = descriptorResolver.resolveObjectDeclarationAsPropertyDescriptor(
                             scopeForFunctions, namespaceLike.getOwnerForChildren(), declaration, context.getObjects().get(declaration), trace);
 
@@ -260,7 +260,7 @@ public class DeclarationResolver {
                 }
 
                 @Override
-                public void visitEnumEntry(JetEnumEntry enumEntry) {
+                public void visitEnumEntry(@NotNull JetEnumEntry enumEntry) {
                     // FIX: Bad cast
                     MutableClassDescriptorLite classObjectDescriptor =
                             ((MutableClassDescriptorLite)namespaceLike.getOwnerForChildren()).getClassObjectDescriptor();
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/TypeHierarchyResolver.java b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/TypeHierarchyResolver.java
index 2349b1c78bc..bd566535aef 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/TypeHierarchyResolver.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/TypeHierarchyResolver.java
@@ -440,7 +440,7 @@ public class TypeHierarchyResolver {
         }
 
         @Override
-        public void visitJetFile(JetFile file) {
+        public void visitJetFile(@NotNull JetFile file) {
             NamespaceDescriptorImpl namespaceDescriptor = namespaceFactory.createNamespaceDescriptorPathIfNeeded(
                     file, outerScope, RedeclarationHandler.DO_NOTHING);
             context.getNamespaceDescriptors().put(file, namespaceDescriptor);
@@ -458,14 +458,14 @@ public class TypeHierarchyResolver {
         }
 
         @Override
-        public void visitClass(JetClass klass) {
+        public void visitClass(@NotNull JetClass klass) {
             MutableClassDescriptor mutableClassDescriptor = createClassDescriptorForClass(klass, owner.getOwnerForChildren());
 
             owner.addClassifierDescriptor(mutableClassDescriptor);
         }
 
         @Override
-        public void visitObjectDeclaration(JetObjectDeclaration declaration) {
+        public void visitObjectDeclaration(@NotNull JetObjectDeclaration declaration) {
             MutableClassDescriptor objectDescriptor =
                     createClassDescriptorForObject(declaration, owner, outerScope, JetPsiUtil.safeName(declaration.getName()),
                                                    ClassKind.OBJECT);
@@ -474,7 +474,7 @@ public class TypeHierarchyResolver {
         }
 
         @Override
-        public void visitEnumEntry(JetEnumEntry enumEntry) {
+        public void visitEnumEntry(@NotNull JetEnumEntry enumEntry) {
             // TODO: Bad casting
             MutableClassDescriptorLite ownerClassDescriptor = (MutableClassDescriptorLite) owner.getOwnerForChildren();
             MutableClassDescriptorLite classObjectDescriptor = ownerClassDescriptor.getClassObjectDescriptor();
@@ -484,12 +484,12 @@ public class TypeHierarchyResolver {
         }
 
         @Override
-        public void visitTypedef(JetTypedef typedef) {
+        public void visitTypedef(@NotNull JetTypedef typedef) {
             trace.report(UNSUPPORTED.on(typedef, "TypeHierarchyResolver"));
         }
 
         @Override
-        public void visitClassObject(JetClassObject classObject) {
+        public void visitClassObject(@NotNull JetClassObject classObject) {
             JetObjectDeclaration objectDeclaration = classObject.getObjectDeclaration();
             if (objectDeclaration != null) {
                 Name classObjectName = getClassObjectName(owner.getOwnerForChildren().getName());
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/TypeResolver.java b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/TypeResolver.java
index e95e8e23785..58911656f0c 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/resolve/TypeResolver.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/resolve/TypeResolver.java
@@ -99,7 +99,7 @@ public class TypeResolver {
         if (typeElement != null) {
             typeElement.accept(new JetVisitorVoid() {
                 @Override
-                public void visitUserType(JetUserType type) {
+                public void visitUserType(@NotNull JetUserType type) {
                     JetSimpleNameExpression referenceExpression = type.getReferenceExpression();
                     String referencedName = type.getReferencedName();
                     if (referenceExpression == null || referencedName == null) {
@@ -191,7 +191,7 @@ public class TypeResolver {
                 }
 
                 @Override
-                public void visitNullableType(JetNullableType nullableType) {
+                public void visitNullableType(@NotNull JetNullableType nullableType) {
                     PossiblyBareType baseType = resolveTypeElement(c, annotations, nullableType.getInnerType());
                     if (baseType.isNullable()) {
                         c.trace.report(REDUNDANT_NULLABLE.on(nullableType));
@@ -203,7 +203,7 @@ public class TypeResolver {
                 }
 
                 @Override
-                public void visitFunctionType(JetFunctionType type) {
+                public void visitFunctionType(@NotNull JetFunctionType type) {
                     JetTypeReference receiverTypeRef = type.getReceiverTypeRef();
                     JetType receiverType = receiverTypeRef == null ? null : resolveType(c.noBareTypes(), receiverTypeRef);
 
@@ -224,7 +224,7 @@ public class TypeResolver {
                 }
 
                 @Override
-                public void visitJetElement(JetElement element) {
+                public void visitJetElement(@NotNull JetElement element) {
                     c.trace.report(UNSUPPORTED.on(element, "Self-types are not supported yet"));
                 }
             });
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/types/expressions/BasicExpressionTypingVisitor.java b/compiler/frontend/src/org/jetbrains/jet/lang/types/expressions/BasicExpressionTypingVisitor.java
index 6a650bd68c0..0406a2cf0a0 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/types/expressions/BasicExpressionTypingVisitor.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/types/expressions/BasicExpressionTypingVisitor.java
@@ -1143,7 +1143,7 @@ public class BasicExpressionTypingVisitor extends ExpressionTypingVisitor {
             entry.accept(new JetVisitorVoid() {
 
                 @Override
-                public void visitStringTemplateEntryWithExpression(JetStringTemplateEntryWithExpression entry) {
+                public void visitStringTemplateEntryWithExpression(@NotNull JetStringTemplateEntryWithExpression entry) {
                     JetExpression entryExpression = entry.getExpression();
                     if (entryExpression != null) {
                         JetTypeInfo typeInfo = facade.getTypeInfo(entryExpression, context.replaceDataFlowInfo(dataFlowInfo[0]));
@@ -1153,12 +1153,12 @@ public class BasicExpressionTypingVisitor extends ExpressionTypingVisitor {
                 }
 
                 @Override
-                public void visitLiteralStringTemplateEntry(JetLiteralStringTemplateEntry entry) {
+                public void visitLiteralStringTemplateEntry(@NotNull JetLiteralStringTemplateEntry entry) {
                     builder.append(entry.getText());
                 }
 
                 @Override
-                public void visitEscapeStringTemplateEntry(JetEscapeStringTemplateEntry entry) {
+                public void visitEscapeStringTemplateEntry(@NotNull JetEscapeStringTemplateEntry entry) {
                     CompileTimeConstant<?> character = CompileTimeConstantResolver.escapedStringToCharValue(entry.getText(), entry);
                     if (character instanceof ErrorValue) {
                         assert character instanceof ErrorValueWithDiagnostic;
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/types/expressions/DataFlowUtils.java b/compiler/frontend/src/org/jetbrains/jet/lang/types/expressions/DataFlowUtils.java
index ae4b1fd54a3..64c41bb9364 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/types/expressions/DataFlowUtils.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/types/expressions/DataFlowUtils.java
@@ -51,14 +51,14 @@ public class DataFlowUtils {
         final Ref<DataFlowInfo> result = new Ref<DataFlowInfo>(null);
         condition.accept(new JetVisitorVoid() {
             @Override
-            public void visitIsExpression(JetIsExpression expression) {
+            public void visitIsExpression(@NotNull JetIsExpression expression) {
                 if (conditionValue && !expression.isNegated() || !conditionValue && expression.isNegated()) {
                     result.set(context.trace.get(BindingContext.DATAFLOW_INFO_AFTER_CONDITION, expression));
                 }
             }
 
             @Override
-            public void visitBinaryExpression(JetBinaryExpression expression) {
+            public void visitBinaryExpression(@NotNull JetBinaryExpression expression) {
                 IElementType operationToken = expression.getOperationToken();
                 if (OperatorConventions.BOOLEAN_OPERATIONS.containsKey(operationToken)) {
                     DataFlowInfo dataFlowInfo = extractDataFlowInfoFromCondition(expression.getLeft(), conditionValue, context);
@@ -110,7 +110,7 @@ public class DataFlowUtils {
             }
 
             @Override
-            public void visitUnaryExpression(JetUnaryExpression expression) {
+            public void visitUnaryExpression(@NotNull JetUnaryExpression expression) {
                 IElementType operationTokenType = expression.getOperationReference().getReferencedNameElementType();
                 if (operationTokenType == JetTokens.EXCL) {
                     JetExpression baseExpression = expression.getBaseExpression();
@@ -121,7 +121,7 @@ public class DataFlowUtils {
             }
 
             @Override
-            public void visitParenthesizedExpression(JetParenthesizedExpression expression) {
+            public void visitParenthesizedExpression(@NotNull JetParenthesizedExpression expression) {
                 JetExpression body = expression.getExpression();
                 if (body != null) {
                     body.accept(this);
diff --git a/compiler/frontend/src/org/jetbrains/jet/lang/types/expressions/PatternMatchingTypingVisitor.java b/compiler/frontend/src/org/jetbrains/jet/lang/types/expressions/PatternMatchingTypingVisitor.java
index 6b83e599948..ace7291be8c 100644
--- a/compiler/frontend/src/org/jetbrains/jet/lang/types/expressions/PatternMatchingTypingVisitor.java
+++ b/compiler/frontend/src/org/jetbrains/jet/lang/types/expressions/PatternMatchingTypingVisitor.java
@@ -178,7 +178,7 @@ public class PatternMatchingTypingVisitor extends ExpressionTypingVisitor {
         final Ref<DataFlowInfos> newDataFlowInfo = new Ref<DataFlowInfos>(noChange(context));
         condition.accept(new JetVisitorVoid() {
             @Override
-            public void visitWhenConditionInRange(JetWhenConditionInRange condition) {
+            public void visitWhenConditionInRange(@NotNull JetWhenConditionInRange condition) {
                 JetExpression rangeExpression = condition.getRangeExpression();
                 if (rangeExpression == null) return;
                 if (expectedCondition) {
@@ -197,7 +197,7 @@ public class PatternMatchingTypingVisitor extends ExpressionTypingVisitor {
             }
 
             @Override
-            public void visitWhenConditionIsPattern(JetWhenConditionIsPattern condition) {
+            public void visitWhenConditionIsPattern(@NotNull JetWhenConditionIsPattern condition) {
                 if (expectedCondition) {
                     context.trace.report(EXPECTED_CONDITION.on(condition));
                 }
@@ -213,7 +213,7 @@ public class PatternMatchingTypingVisitor extends ExpressionTypingVisitor {
             }
 
             @Override
-            public void visitWhenConditionWithExpression(JetWhenConditionWithExpression condition) {
+            public void visitWhenConditionWithExpression(@NotNull JetWhenConditionWithExpression condition) {
                 JetExpression expression = condition.getExpression();
                 if (expression != null) {
                     newDataFlowInfo.set(checkTypeForExpressionCondition(context, expression, subjectType, subjectExpression == null,
@@ -222,7 +222,7 @@ public class PatternMatchingTypingVisitor extends ExpressionTypingVisitor {
             }
 
             @Override
-            public void visitJetElement(JetElement element) {
+            public void visitJetElement(@NotNull JetElement element) {
                 context.trace.report(UNSUPPORTED.on(element, getClass().getCanonicalName()));
             }
         });
diff --git a/compiler/tests/org/jetbrains/jet/lang/resolve/lazy/AbstractLazyResolveDescriptorRendererTest.java b/compiler/tests/org/jetbrains/jet/lang/resolve/lazy/AbstractLazyResolveDescriptorRendererTest.java
index 33cf5be9695..7a43f4be112 100644
--- a/compiler/tests/org/jetbrains/jet/lang/resolve/lazy/AbstractLazyResolveDescriptorRendererTest.java
+++ b/compiler/tests/org/jetbrains/jet/lang/resolve/lazy/AbstractLazyResolveDescriptorRendererTest.java
@@ -63,7 +63,7 @@ public abstract class AbstractLazyResolveDescriptorRendererTest extends KotlinTe
         final List<DeclarationDescriptor> descriptors = new ArrayList<DeclarationDescriptor>();
         psiFile.accept(new JetVisitorVoid() {
             @Override
-            public void visitJetFile(JetFile file) {
+            public void visitJetFile(@NotNull JetFile file) {
                 String qualifiedName = file.getNamespaceHeader().getQualifiedName();
                 if (!qualifiedName.isEmpty()) {
                     NamespaceDescriptor packageDescriptor = resolveSession.getPackageDescriptorByFqName(new FqName(qualifiedName));
@@ -73,12 +73,12 @@ public abstract class AbstractLazyResolveDescriptorRendererTest extends KotlinTe
             }
 
             @Override
-            public void visitClassObject(JetClassObject classObject) {
+            public void visitClassObject(@NotNull JetClassObject classObject) {
                 classObject.acceptChildren(this);
             }
 
             @Override
-            public void visitParameter(JetParameter parameter) {
+            public void visitParameter(@NotNull JetParameter parameter) {
                 PsiElement declaringElement = parameter.getParent().getParent();
                 if (declaringElement instanceof JetFunctionType) {
                     return;
@@ -108,7 +108,7 @@ public abstract class AbstractLazyResolveDescriptorRendererTest extends KotlinTe
             }
 
             @Override
-            public void visitPropertyAccessor(JetPropertyAccessor accessor) {
+            public void visitPropertyAccessor(@NotNull JetPropertyAccessor accessor) {
                 JetProperty parent = (JetProperty) accessor.getParent();
                 PropertyDescriptor propertyDescriptor = (PropertyDescriptor) resolveSession.resolveToDescriptor(parent);
                 if (accessor.isGetter()) {
@@ -120,7 +120,7 @@ public abstract class AbstractLazyResolveDescriptorRendererTest extends KotlinTe
             }
 
             @Override
-            public void visitDeclaration(JetDeclaration element) {
+            public void visitDeclaration(@NotNull JetDeclaration element) {
                 DeclarationDescriptor descriptor = resolveSession.resolveToDescriptor(element);
                 descriptors.add(descriptor);
                 if (descriptor instanceof ClassDescriptor) {
@@ -130,7 +130,7 @@ public abstract class AbstractLazyResolveDescriptorRendererTest extends KotlinTe
             }
 
             @Override
-            public void visitJetElement(JetElement element) {
+            public void visitJetElement(@NotNull JetElement element) {
                 element.acceptChildren(this);
             }
         });
diff --git a/compiler/tests/org/jetbrains/jet/parsing/AbstractJetParsingTest.java b/compiler/tests/org/jetbrains/jet/parsing/AbstractJetParsingTest.java
index 69b60d24359..97453274070 100644
--- a/compiler/tests/org/jetbrains/jet/parsing/AbstractJetParsingTest.java
+++ b/compiler/tests/org/jetbrains/jet/parsing/AbstractJetParsingTest.java
@@ -77,7 +77,7 @@ public abstract class AbstractJetParsingTest extends ParsingTestCase {
 
         myFile.acceptChildren(new JetVisitorVoid() {
             @Override
-            public void visitJetElement(JetElement element) {
+            public void visitJetElement(@NotNull JetElement element) {
                 element.acceptChildren(this);
                 try {
                     checkPsiGetters(element);
diff --git a/compiler/tests/org/jetbrains/jet/renderer/DescriptorRendererTest.java b/compiler/tests/org/jetbrains/jet/renderer/DescriptorRendererTest.java
index 11a21910c73..7f572f8b646 100644
--- a/compiler/tests/org/jetbrains/jet/renderer/DescriptorRendererTest.java
+++ b/compiler/tests/org/jetbrains/jet/renderer/DescriptorRendererTest.java
@@ -18,6 +18,7 @@ package org.jetbrains.jet.renderer;
 
 import com.intellij.openapi.editor.Document;
 import com.intellij.openapi.editor.impl.DocumentImpl;
+import org.jetbrains.annotations.NotNull;
 import org.jetbrains.jet.ConfigurationKind;
 import org.jetbrains.jet.JetLiteFixture;
 import org.jetbrains.jet.JetTestCaseBuilder;
@@ -95,7 +96,7 @@ public class DescriptorRendererTest extends JetLiteFixture {
         final List<DeclarationDescriptor> descriptors = new ArrayList<DeclarationDescriptor>();
         psiFile.acceptChildren(new JetVisitorVoid() {
             @Override
-            public void visitJetElement(JetElement element) {
+            public void visitJetElement(@NotNull JetElement element) {
                 DeclarationDescriptor descriptor = bindingContext.get(BindingContext.DECLARATION_TO_DESCRIPTOR, element);
                 if (descriptor != null) {
                     descriptors.add(descriptor);
diff --git a/idea/src/org/jetbrains/jet/plugin/codeInsight/ReferenceToClassesShortening.java b/idea/src/org/jetbrains/jet/plugin/codeInsight/ReferenceToClassesShortening.java
index 037d5b06604..37a16fd7dab 100644
--- a/idea/src/org/jetbrains/jet/plugin/codeInsight/ReferenceToClassesShortening.java
+++ b/idea/src/org/jetbrains/jet/plugin/codeInsight/ReferenceToClassesShortening.java
@@ -17,6 +17,7 @@
 package org.jetbrains.jet.plugin.codeInsight;
 
 import com.intellij.psi.PsiDocumentManager;
+import org.jetbrains.annotations.NotNull;
 import org.jetbrains.jet.lang.descriptors.ClassDescriptor;
 import org.jetbrains.jet.lang.descriptors.ClassifierDescriptor;
 import org.jetbrains.jet.lang.descriptors.DeclarationDescriptor;
@@ -44,12 +45,12 @@ public class ReferenceToClassesShortening {
         for (JetElement element : elementsToCompact) {
             element.accept(new JetVisitorVoid() {
                 @Override
-                public void visitJetElement(JetElement element) {
+                public void visitJetElement(@NotNull JetElement element) {
                     element.acceptChildren(this);
                 }
 
                 @Override
-                public void visitTypeReference(JetTypeReference typeReference) {
+                public void visitTypeReference(@NotNull JetTypeReference typeReference) {
                     super.visitTypeReference(typeReference);
 
                     JetTypeElement typeElement = typeReference.getTypeElement();
diff --git a/idea/src/org/jetbrains/jet/plugin/codeInsight/upDownMover/JetDeclarationMover.java b/idea/src/org/jetbrains/jet/plugin/codeInsight/upDownMover/JetDeclarationMover.java
index dd0a71bf8d9..fda0d2b9b09 100644
--- a/idea/src/org/jetbrains/jet/plugin/codeInsight/upDownMover/JetDeclarationMover.java
+++ b/idea/src/org/jetbrains/jet/plugin/codeInsight/upDownMover/JetDeclarationMover.java
@@ -34,7 +34,7 @@ public class JetDeclarationMover extends AbstractJetUpDownMover {
         declaration.accept(
                 new JetVisitorVoid() {
                     @Override
-                    public void visitAnonymousInitializer(JetClassInitializer initializer) {
+                    public void visitAnonymousInitializer(@NotNull JetClassInitializer initializer) {
                         PsiElement brace = initializer.getOpenBraceNode();
                         if (brace != null) {
                             memberSuspects.add(brace);
@@ -42,13 +42,13 @@ public class JetDeclarationMover extends AbstractJetUpDownMover {
                     }
 
                     @Override
-                    public void visitClassObject(JetClassObject classObject) {
+                    public void visitClassObject(@NotNull JetClassObject classObject) {
                         PsiElement classKeyword = classObject.getClassKeywordNode();
                         if (classKeyword != null) memberSuspects.add(classKeyword);
                     }
 
                     @Override
-                    public void visitNamedFunction(JetNamedFunction function) {
+                    public void visitNamedFunction(@NotNull JetNamedFunction function) {
                         PsiElement equalsToken = function.getEqualsToken();
                         if (equalsToken != null) memberSuspects.add(equalsToken);
 
@@ -63,7 +63,7 @@ public class JetDeclarationMover extends AbstractJetUpDownMover {
                     }
 
                     @Override
-                    public void visitProperty(JetProperty property) {
+                    public void visitProperty(@NotNull JetProperty property) {
                         PsiElement valOrVarNode = property.getValOrVarNode().getPsi();
                         if (valOrVarNode != null) memberSuspects.add(valOrVarNode);
 
diff --git a/idea/src/org/jetbrains/jet/plugin/editor/importOptimizer/JetImportOptimizer.java b/idea/src/org/jetbrains/jet/plugin/editor/importOptimizer/JetImportOptimizer.java
index 547b99d3f77..23cef18cf00 100644
--- a/idea/src/org/jetbrains/jet/plugin/editor/importOptimizer/JetImportOptimizer.java
+++ b/idea/src/org/jetbrains/jet/plugin/editor/importOptimizer/JetImportOptimizer.java
@@ -116,7 +116,7 @@ public class JetImportOptimizer implements ImportOptimizer {
             }
 
             @Override
-            public void visitUserType(JetUserType type) {
+            public void visitUserType(@NotNull JetUserType type) {
                 if (type.getQualifier() == null) {
                     super.visitUserType(type);
                 }
@@ -130,7 +130,7 @@ public class JetImportOptimizer implements ImportOptimizer {
             }
 
             @Override
-            public void visitReferenceExpression(JetReferenceExpression expression) {
+            public void visitReferenceExpression(@NotNull JetReferenceExpression expression) {
                 if (PsiTreeUtil.getParentOfType(expression, JetImportDirective.class) == null &&
                         PsiTreeUtil.getParentOfType(expression, JetNamespaceHeader.class) == null) {
 
@@ -161,7 +161,7 @@ public class JetImportOptimizer implements ImportOptimizer {
             }
 
             @Override
-            public void visitForExpression(JetForExpression expression) {
+            public void visitForExpression(@NotNull JetForExpression expression) {
                 BindingContext context = AnalyzerFacadeWithCache.getContextForElement(expression);
                 ResolvedCall<FunctionDescriptor> resolvedCall = context.get(BindingContext.LOOP_RANGE_ITERATOR_RESOLVED_CALL, expression.getLoopRange());
                 addResolvedCallFqName(resolvedCall);
@@ -170,7 +170,7 @@ public class JetImportOptimizer implements ImportOptimizer {
             }
 
             @Override
-            public void visitMultiDeclaration(JetMultiDeclaration declaration) {
+            public void visitMultiDeclaration(@NotNull JetMultiDeclaration declaration) {
                 BindingContext context = AnalyzerFacadeWithCache.getContextForElement(declaration);
                 List<JetMultiDeclarationEntry> entries = declaration.getEntries();
                 for (JetMultiDeclarationEntry entry : entries) {
diff --git a/idea/src/org/jetbrains/jet/plugin/hierarchy/calls/CalleeReferenceVisitorBase.java b/idea/src/org/jetbrains/jet/plugin/hierarchy/calls/CalleeReferenceVisitorBase.java
index 0574ef7bd73..bd4b26faa90 100644
--- a/idea/src/org/jetbrains/jet/plugin/hierarchy/calls/CalleeReferenceVisitorBase.java
+++ b/idea/src/org/jetbrains/jet/plugin/hierarchy/calls/CalleeReferenceVisitorBase.java
@@ -19,6 +19,7 @@ package org.jetbrains.jet.plugin.hierarchy.calls;
 import com.intellij.psi.PsiElement;
 import com.intellij.psi.PsiMethod;
 import com.intellij.psi.util.PsiTreeUtil;
+import org.jetbrains.annotations.NotNull;
 import org.jetbrains.jet.lang.descriptors.DeclarationDescriptor;
 import org.jetbrains.jet.lang.descriptors.FunctionDescriptor;
 import org.jetbrains.jet.lang.descriptors.PropertyDescriptor;
@@ -38,14 +39,14 @@ public abstract class CalleeReferenceVisitorBase extends JetTreeVisitorVoid {
     protected abstract void processDeclaration(JetReferenceExpression reference, PsiElement declaration);
 
     @Override
-    public void visitJetElement(JetElement element) {
+    public void visitJetElement(@NotNull JetElement element) {
         if (deepTraversal || !(element instanceof JetClassOrObject || element instanceof JetNamedFunction)) {
             super.visitJetElement(element);
         }
     }
 
     @Override
-    public void visitSimpleNameExpression(JetSimpleNameExpression expression) {
+    public void visitSimpleNameExpression(@NotNull JetSimpleNameExpression expression) {
         DeclarationDescriptor descriptor = bindingContext.get(BindingContext.REFERENCE_TARGET, expression);
         if (descriptor == null) return;
 
diff --git a/idea/src/org/jetbrains/jet/plugin/highlighter/DeprecatedAnnotationVisitor.java b/idea/src/org/jetbrains/jet/plugin/highlighter/DeprecatedAnnotationVisitor.java
index 040f3c337b2..54f6078c7f3 100644
--- a/idea/src/org/jetbrains/jet/plugin/highlighter/DeprecatedAnnotationVisitor.java
+++ b/idea/src/org/jetbrains/jet/plugin/highlighter/DeprecatedAnnotationVisitor.java
@@ -51,12 +51,12 @@ public class DeprecatedAnnotationVisitor extends AfterAnalysisHighlightingVisito
     }
 
     @Override
-    public void visitSuperExpression(JetSuperExpression expression) {
+    public void visitSuperExpression(@NotNull JetSuperExpression expression) {
         // Deprecated for super expression. Unnecessary to mark it as Deprecated
     }
 
     @Override
-    public void visitReferenceExpression(JetReferenceExpression expression) {
+    public void visitReferenceExpression(@NotNull JetReferenceExpression expression) {
         super.visitReferenceExpression(expression);
         ResolvedCall resolvedCall = bindingContext.get(BindingContext.RESOLVED_CALL, expression);
         if (resolvedCall != null && resolvedCall instanceof VariableAsFunctionResolvedCall) {
diff --git a/idea/src/org/jetbrains/jet/plugin/highlighter/FunctionsHighlightingVisitor.java b/idea/src/org/jetbrains/jet/plugin/highlighter/FunctionsHighlightingVisitor.java
index c81a0ba1f2a..377c4697a7c 100644
--- a/idea/src/org/jetbrains/jet/plugin/highlighter/FunctionsHighlightingVisitor.java
+++ b/idea/src/org/jetbrains/jet/plugin/highlighter/FunctionsHighlightingVisitor.java
@@ -18,6 +18,7 @@ package org.jetbrains.jet.plugin.highlighter;
 
 import com.intellij.lang.annotation.AnnotationHolder;
 import com.intellij.psi.PsiElement;
+import org.jetbrains.annotations.NotNull;
 import org.jetbrains.jet.lang.descriptors.*;
 import org.jetbrains.jet.lang.psi.*;
 import org.jetbrains.jet.lang.resolve.BindingContext;
@@ -34,7 +35,7 @@ public class FunctionsHighlightingVisitor extends AfterAnalysisHighlightingVisit
     }
 
     @Override
-    public void visitNamedFunction(JetNamedFunction function) {
+    public void visitNamedFunction(@NotNull JetNamedFunction function) {
         PsiElement nameIdentifier = function.getNameIdentifier();
         if (nameIdentifier != null) {
             JetPsiChecker.highlightName(holder, nameIdentifier, JetHighlightingColors.FUNCTION_DECLARATION);
@@ -44,7 +45,7 @@ public class FunctionsHighlightingVisitor extends AfterAnalysisHighlightingVisit
     }
 
     @Override
-    public void visitDelegationToSuperCallSpecifier(JetDelegatorToSuperCall call) {
+    public void visitDelegationToSuperCallSpecifier(@NotNull JetDelegatorToSuperCall call) {
         JetConstructorCalleeExpression calleeExpression = call.getCalleeExpression();
         JetTypeReference typeRef = calleeExpression.getTypeReference();
         if (typeRef != null) {
@@ -60,7 +61,7 @@ public class FunctionsHighlightingVisitor extends AfterAnalysisHighlightingVisit
     }
 
     @Override
-    public void visitCallExpression(JetCallExpression expression) {
+    public void visitCallExpression(@NotNull JetCallExpression expression) {
         JetExpression callee = expression.getCalleeExpression();
         if (callee instanceof JetReferenceExpression) {
             ResolvedCall<? extends CallableDescriptor> resolvedCall =
diff --git a/idea/src/org/jetbrains/jet/plugin/highlighter/LabelsHighlightingVisitor.java b/idea/src/org/jetbrains/jet/plugin/highlighter/LabelsHighlightingVisitor.java
index 028f597987d..bd35678166f 100644
--- a/idea/src/org/jetbrains/jet/plugin/highlighter/LabelsHighlightingVisitor.java
+++ b/idea/src/org/jetbrains/jet/plugin/highlighter/LabelsHighlightingVisitor.java
@@ -17,6 +17,7 @@
 package org.jetbrains.jet.plugin.highlighter;
 
 import com.intellij.lang.annotation.AnnotationHolder;
+import org.jetbrains.annotations.NotNull;
 import org.jetbrains.jet.lang.psi.JetLabelQualifiedExpression;
 import org.jetbrains.jet.lang.psi.JetPrefixExpression;
 import org.jetbrains.jet.lang.psi.JetSimpleNameExpression;
@@ -28,7 +29,7 @@ class LabelsHighlightingVisitor extends HighlightingVisitor {
     }
 
     @Override
-    public void visitPrefixExpression(JetPrefixExpression expression) {
+    public void visitPrefixExpression(@NotNull JetPrefixExpression expression) {
         JetSimpleNameExpression operationSign = expression.getOperationReference();
         if (JetTokens.LABELS.contains(operationSign.getReferencedNameElementType())) {
             JetPsiChecker.highlightName(holder, operationSign, JetHighlightingColors.LABEL);
@@ -36,7 +37,7 @@ class LabelsHighlightingVisitor extends HighlightingVisitor {
     }
 
     @Override
-    public void visitLabelQualifiedExpression(JetLabelQualifiedExpression expression) {
+    public void visitLabelQualifiedExpression(@NotNull JetLabelQualifiedExpression expression) {
         JetSimpleNameExpression targetLabel = expression.getTargetLabel();
         if (targetLabel != null) {
             JetPsiChecker.highlightName(holder, targetLabel, JetHighlightingColors.LABEL);
diff --git a/idea/src/org/jetbrains/jet/plugin/highlighter/PropertiesHighlightingVisitor.java b/idea/src/org/jetbrains/jet/plugin/highlighter/PropertiesHighlightingVisitor.java
index 041dbf6cd7f..83b1e9cb941 100644
--- a/idea/src/org/jetbrains/jet/plugin/highlighter/PropertiesHighlightingVisitor.java
+++ b/idea/src/org/jetbrains/jet/plugin/highlighter/PropertiesHighlightingVisitor.java
@@ -34,7 +34,7 @@ class PropertiesHighlightingVisitor extends AfterAnalysisHighlightingVisitor {
     }
 
     @Override
-    public void visitSimpleNameExpression(JetSimpleNameExpression expression) {
+    public void visitSimpleNameExpression(@NotNull JetSimpleNameExpression expression) {
         if (expression.getParent() instanceof JetThisExpression) {
             return;
         }
diff --git a/idea/src/org/jetbrains/jet/plugin/highlighter/SoftKeywordsHighlightingVisitor.java b/idea/src/org/jetbrains/jet/plugin/highlighter/SoftKeywordsHighlightingVisitor.java
index 515590c89a3..5823418f042 100644
--- a/idea/src/org/jetbrains/jet/plugin/highlighter/SoftKeywordsHighlightingVisitor.java
+++ b/idea/src/org/jetbrains/jet/plugin/highlighter/SoftKeywordsHighlightingVisitor.java
@@ -23,6 +23,7 @@ import com.intellij.openapi.editor.colors.TextAttributesKey;
 import com.intellij.psi.PsiElement;
 import com.intellij.psi.impl.source.tree.LeafPsiElement;
 import com.intellij.psi.tree.IElementType;
+import org.jetbrains.annotations.NotNull;
 import org.jetbrains.jet.lang.psi.*;
 import org.jetbrains.jet.lexer.JetTokens;
 
@@ -49,7 +50,7 @@ class SoftKeywordsHighlightingVisitor extends HighlightingVisitor {
     }
 
     @Override
-    public void visitFunctionLiteralExpression(JetFunctionLiteralExpression expression) {
+    public void visitFunctionLiteralExpression(@NotNull JetFunctionLiteralExpression expression) {
         if (ApplicationManager.getApplication().isUnitTestMode()) return;
         JetFunctionLiteral functionLiteral = expression.getFunctionLiteral();
         holder.createInfoAnnotation(functionLiteral.getOpenBraceNode(), null).setTextAttributes(JetHighlightingColors.FUNCTION_LITERAL_BRACES_AND_ARROW);
diff --git a/idea/src/org/jetbrains/jet/plugin/highlighter/TypeKindHighlightingVisitor.java b/idea/src/org/jetbrains/jet/plugin/highlighter/TypeKindHighlightingVisitor.java
index 8cd7ecd5646..1def1ac26cf 100644
--- a/idea/src/org/jetbrains/jet/plugin/highlighter/TypeKindHighlightingVisitor.java
+++ b/idea/src/org/jetbrains/jet/plugin/highlighter/TypeKindHighlightingVisitor.java
@@ -31,7 +31,7 @@ class TypeKindHighlightingVisitor extends AfterAnalysisHighlightingVisitor {
     }
 
     @Override
-    public void visitSimpleNameExpression(JetSimpleNameExpression expression) {
+    public void visitSimpleNameExpression(@NotNull JetSimpleNameExpression expression) {
         PsiReference ref = expression.getReference();
         if (ref == null) return;
         if (JetPsiChecker.isNamesHighlightingEnabled()) {
@@ -50,7 +50,7 @@ class TypeKindHighlightingVisitor extends AfterAnalysisHighlightingVisitor {
     }
 
     @Override
-    public void visitTypeParameter(JetTypeParameter parameter) {
+    public void visitTypeParameter(@NotNull JetTypeParameter parameter) {
         PsiElement identifier = parameter.getNameIdentifier();
         if (identifier != null) {
             JetPsiChecker.highlightName(holder, identifier, JetHighlightingColors.TYPE_PARAMETER);
@@ -59,7 +59,7 @@ class TypeKindHighlightingVisitor extends AfterAnalysisHighlightingVisitor {
     }
 
     @Override
-    public void visitClass(JetClass klass) {
+    public void visitClass(@NotNull JetClass klass) {
         PsiElement identifier = klass.getNameIdentifier();
         ClassDescriptor classDescriptor = bindingContext.get(BindingContext.CLASS, klass);
         if (identifier != null && classDescriptor != null) {
diff --git a/idea/src/org/jetbrains/jet/plugin/highlighter/VariablesHighlightingVisitor.java b/idea/src/org/jetbrains/jet/plugin/highlighter/VariablesHighlightingVisitor.java
index 28cf2c3d1c6..e0fbdf83568 100644
--- a/idea/src/org/jetbrains/jet/plugin/highlighter/VariablesHighlightingVisitor.java
+++ b/idea/src/org/jetbrains/jet/plugin/highlighter/VariablesHighlightingVisitor.java
@@ -59,7 +59,7 @@ class VariablesHighlightingVisitor extends AfterAnalysisHighlightingVisitor {
     }
 
     @Override
-    public void visitParameter(JetParameter parameter) {
+    public void visitParameter(@NotNull JetParameter parameter) {
         visitVariableDeclaration(parameter);
         super.visitParameter(parameter);
     }
diff --git a/idea/src/org/jetbrains/jet/plugin/quickfix/MigrateSureInProjectFix.java b/idea/src/org/jetbrains/jet/plugin/quickfix/MigrateSureInProjectFix.java
index 79b2ba0cffe..2df69d0b26a 100644
--- a/idea/src/org/jetbrains/jet/plugin/quickfix/MigrateSureInProjectFix.java
+++ b/idea/src/org/jetbrains/jet/plugin/quickfix/MigrateSureInProjectFix.java
@@ -106,7 +106,7 @@ public class MigrateSureInProjectFix extends JetIntentionAction<PsiElement> {
             declaration.acceptChildren(new JetVisitorVoid() {
 
                 @Override
-                public void visitCallExpression(JetCallExpression expression) {
+                public void visitCallExpression(@NotNull JetCallExpression expression) {
                     expression.acceptChildren(this);
 
                     if (!isUnresolvedSure(expression.getCalleeExpression())) return;
diff --git a/idea/src/org/jetbrains/jet/plugin/quickfix/RemoveValVarFromParametersFix.java b/idea/src/org/jetbrains/jet/plugin/quickfix/RemoveValVarFromParametersFix.java
index 33aa7ca40fa..4066aeab9e7 100644
--- a/idea/src/org/jetbrains/jet/plugin/quickfix/RemoveValVarFromParametersFix.java
+++ b/idea/src/org/jetbrains/jet/plugin/quickfix/RemoveValVarFromParametersFix.java
@@ -57,7 +57,7 @@ public class RemoveValVarFromParametersFix implements IntentionAction {
         for (JetFile jetFile : files) {
             jetFile.acceptChildren(new JetVisitorVoid() {
                 @Override
-                public void visitParameter(JetParameter parameter) {
+                public void visitParameter(@NotNull JetParameter parameter) {
                     visitJetElement(parameter); // run recursively for children
 
                     PsiElement parent = parameter.getParent();
@@ -75,7 +75,7 @@ public class RemoveValVarFromParametersFix implements IntentionAction {
                 }
 
                 @Override
-                public void visitJetElement(JetElement element) {
+                public void visitJetElement(@NotNull JetElement element) {
                     element.acceptChildren(this);
                 }
             });
diff --git a/idea/src/org/jetbrains/jet/plugin/refactoring/JetNameSuggester.java b/idea/src/org/jetbrains/jet/plugin/refactoring/JetNameSuggester.java
index 580693039c7..6fdb5eedc9f 100644
--- a/idea/src/org/jetbrains/jet/plugin/refactoring/JetNameSuggester.java
+++ b/idea/src/org/jetbrains/jet/plugin/refactoring/JetNameSuggester.java
@@ -19,6 +19,7 @@ package org.jetbrains.jet.plugin.refactoring;
 import com.intellij.openapi.application.ApplicationManager;
 import com.intellij.openapi.util.text.StringUtil;
 import com.intellij.util.ArrayUtil;
+import org.jetbrains.annotations.NotNull;
 import org.jetbrains.jet.lang.descriptors.ClassDescriptor;
 import org.jetbrains.jet.lang.psi.*;
 import org.jetbrains.jet.lang.resolve.BindingContext;
@@ -213,13 +214,13 @@ public class JetNameSuggester {
     private static void addNamesForExpression(final ArrayList<String> result, JetExpression expression, final JetNameValidator validator) {
         expression.accept(new JetVisitorVoid() {
             @Override
-            public void visitQualifiedExpression(JetQualifiedExpression expression) {
+            public void visitQualifiedExpression(@NotNull JetQualifiedExpression expression) {
                 JetExpression selectorExpression = expression.getSelectorExpression();
                 addNamesForExpression(result, selectorExpression, validator);
             }
 
             @Override
-            public void visitSimpleNameExpression(JetSimpleNameExpression expression) {
+            public void visitSimpleNameExpression(@NotNull JetSimpleNameExpression expression) {
                 String referenceName = expression.getReferencedName();
                 if (referenceName.equals(referenceName.toUpperCase())) {
                     addName(result, referenceName, validator);
@@ -230,12 +231,12 @@ public class JetNameSuggester {
             }
 
             @Override
-            public void visitCallExpression(JetCallExpression expression) {
+            public void visitCallExpression(@NotNull JetCallExpression expression) {
                 addNamesForExpression(result, expression.getCalleeExpression(), validator);
             }
 
             @Override
-            public void visitPostfixExpression(JetPostfixExpression expression) {
+            public void visitPostfixExpression(@NotNull JetPostfixExpression expression) {
                 addNamesForExpression(result, expression.getBaseExpression(), validator);
             }
         });
diff --git a/idea/src/org/jetbrains/jet/plugin/refactoring/JetNameValidatorImpl.java b/idea/src/org/jetbrains/jet/plugin/refactoring/JetNameValidatorImpl.java
index 7595c6d9fc5..15f9ce32f4e 100644
--- a/idea/src/org/jetbrains/jet/plugin/refactoring/JetNameValidatorImpl.java
+++ b/idea/src/org/jetbrains/jet/plugin/refactoring/JetNameValidatorImpl.java
@@ -18,6 +18,7 @@ package org.jetbrains.jet.plugin.refactoring;
 
 import com.intellij.openapi.util.Ref;
 import com.intellij.psi.PsiElement;
+import org.jetbrains.annotations.NotNull;
 import org.jetbrains.jet.lang.descriptors.DeclarationDescriptor;
 import org.jetbrains.jet.lang.descriptors.VariableDescriptor;
 import org.jetbrains.jet.lang.psi.JetExpression;
@@ -79,7 +80,7 @@ public class JetNameValidatorImpl extends JetNameValidator {
             }
 
             @Override
-            public void visitExpression(JetExpression expression) {
+            public void visitExpression(@NotNull JetExpression expression) {
                 Collection<DeclarationDescriptor> variants =
                         TipsManager.getVariantsNoReceiver(expression, myBindingContext);
                 for (DeclarationDescriptor variant : variants) {
diff --git a/idea/src/org/jetbrains/jet/plugin/refactoring/introduceVariable/JetIntroduceVariableHandler.java b/idea/src/org/jetbrains/jet/plugin/refactoring/introduceVariable/JetIntroduceVariableHandler.java
index 2884d434844..7a27749d240 100644
--- a/idea/src/org/jetbrains/jet/plugin/refactoring/introduceVariable/JetIntroduceVariableHandler.java
+++ b/idea/src/org/jetbrains/jet/plugin/refactoring/introduceVariable/JetIntroduceVariableHandler.java
@@ -437,13 +437,13 @@ public class JetIntroduceVariableHandler extends JetIntroduceHandlerBase {
 
         JetVisitorVoid visitor = new JetVisitorVoid() {
             @Override
-            public void visitJetElement(JetElement element) {
+            public void visitJetElement(@NotNull JetElement element) {
                 element.acceptChildren(this);
                 super.visitJetElement(element);
             }
 
             @Override
-            public void visitExpression(JetExpression expression) {
+            public void visitExpression(@NotNull JetExpression expression) {
                 if (PsiEquivalenceUtil.areElementsEquivalent(expression, actualExpression, null, new Comparator<PsiElement>() {
                     @Override
                     public int compare(PsiElement element1, PsiElement element2) {