@Nullable
 private static PsiType getTypeFromMapAccess(@NotNull GrReferenceExpressionImpl ref) {
   // map access
   GrExpression qualifier = ref.getQualifierExpression();
   if (qualifier != null) {
     PsiType qType = qualifier.getNominalType();
     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) {
             return TypeConversionUtil.erasure(
                 substitutor.substitute(mapClass.getTypeParameters()[1]));
           }
         }
       }
     }
   }
   return null;
 }