Cleanup (unneeded @Nullable)

java/java-psi-impl/src/com/intellij/psi/impl/compiled/ClsFileImpl.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2016 JetBrains s.r.o.
+ * Copyright 2000-2017 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -370,7 +370,6 @@ public class ClsFileImpl extends ClsRepositoryPsiElement<PsiClassHolderFileStub>
     }
 
     return CachedValuesManager.getCachedValue(this, new CachedValueProvider<PsiElement>() {
-      @Nullable
       @Override
       public Result<PsiElement> compute() {
         PsiElement target = JavaPsiImplementationHelper.getInstance(getProject()).getClsFileNavigationElement(ClsFileImpl.this);