@Nullable
 private static PsiType getTypeFromMapAccess(@NotNull GrReferenceExpression ref) {
   // map access
   GrExpression qualifier = ref.getQualifierExpression();
   if (qualifier instanceof GrReferenceExpression) {
     if (((GrReferenceExpression) qualifier).resolve() instanceof PsiClass) return null;
   }
   if (qualifier != null) {
     PsiType qType = qualifier.getType();
     if (qType instanceof PsiClassType) {
       PsiClassType.ClassResolveResult qResult = ((PsiClassType) qType).resolveGenerics();
       PsiClass clazz = qResult.getElement();
       if (clazz != null) {
         PsiClass mapClass =
             JavaPsiFacade.getInstance(ref.getProject())
                 .findClass(CommonClassNames.JAVA_UTIL_MAP, ref.getResolveScope());
         if (mapClass != null && mapClass.getTypeParameters().length == 2) {
           PsiSubstitutor substitutor =
               TypeConversionUtil.getClassSubstitutor(mapClass, clazz, qResult.getSubstitutor());
           if (substitutor != null) {
             PsiType substituted = substitutor.substitute(mapClass.getTypeParameters()[1]);
             if (substituted != null) {
               return PsiImplUtil.normalizeWildcardTypeByPosition(substituted, ref);
             }
           }
         }
       }
     }
   }
   return null;
 }
 private static PsiClassType getEnumSuperType(
     @NotNull PsiClass psiClass, @NotNull PsiElementFactory factory) {
   PsiClassType superType;
   final PsiManager manager = psiClass.getManager();
   final PsiClass enumClass =
       JavaPsiFacade.getInstance(manager.getProject())
           .findClass("java.lang.Enum", psiClass.getResolveScope());
   if (enumClass == null) {
     try {
       superType = (PsiClassType) factory.createTypeFromText("java.lang.Enum", null);
     } catch (IncorrectOperationException e) {
       superType = null;
     }
   } else {
     final PsiTypeParameter[] typeParameters = enumClass.getTypeParameters();
     PsiSubstitutor substitutor = PsiSubstitutor.EMPTY;
     if (typeParameters.length == 1) {
       substitutor = substitutor.put(typeParameters[0], factory.createType(psiClass));
     }
     superType = new PsiImmediateClassType(enumClass, substitutor);
   }
   return superType;
 }