public static @NlsContexts.DetailedDescription String checkReturnType(PsiMethodReferenceExpression expression, JavaResolveResult result, PsiType functionalInterfaceType) {
    final Ref<@Nls String> errorMessage = Ref.create();
    if (!isReturnTypeCompatible(expression, result, functionalInterfaceType, errorMessage)) {
      return errorMessage.get();
    }
    return null;
  }
public static @NlsContexts.DetailedDescription String checkReturnType(PsiMethodReferenceExpression expression, JavaResolveResult result, PsiType functionalInterfaceType)