@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;
 }
 @Nullable
 private static PsiType getInferredTypes(
     GrReferenceExpressionImpl refExpr, @Nullable PsiElement resolved) {
   final GrExpression qualifier = refExpr.getQualifier();
   if (qualifier == null && !(resolved instanceof PsiClass)) {
     return TypeInferenceHelper.getCurrentContext().getVariableType(refExpr);
   } else if (qualifier != null) {
     // map access
     PsiType qType = qualifier.getType();
     if (qType instanceof PsiClassType && !(qType instanceof GrMapType)) {
       PsiClassType.ClassResolveResult qResult = ((PsiClassType) qType).resolveGenerics();
       PsiClass clazz = qResult.getElement();
       if (clazz != null) {
         PsiClass mapClass =
             JavaPsiFacade.getInstance(refExpr.getProject())
                 .findClass(CommonClassNames.JAVA_UTIL_MAP, refExpr.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;
 }
  @Nullable
  public static PsiType getExpectedClosureReturnType(GrClosableBlock closure) {
    final Set<PsiType> expectedTypes = getDefaultExpectedTypes(closure);

    List<PsiType> expectedReturnTypes = new ArrayList<PsiType>();
    for (PsiType expectedType : expectedTypes) {
      if (!(expectedType instanceof PsiClassType)) return null;

      final PsiClassType.ClassResolveResult resolveResult =
          ((PsiClassType) expectedType).resolveGenerics();
      final PsiClass resolved = resolveResult.getElement();
      if (resolved == null
          || !(GroovyCommonClassNames.GROOVY_LANG_CLOSURE.equals(resolved.getQualifiedName())))
        return null;

      final PsiTypeParameter[] typeParameters = resolved.getTypeParameters();
      if (typeParameters.length != 1) return null;

      final PsiTypeParameter expected = typeParameters[0];
      final PsiType expectedReturnType = resolveResult.getSubstitutor().substitute(expected);
      if (expectedReturnType == PsiType.VOID || expectedReturnType == null) return null;

      expectedReturnTypes.add(expectedReturnType);
    }

    return TypesUtil.getLeastUpperBoundNullable(expectedReturnTypes, closure.getManager());
  }