code: public OperationStatus add(UUID appId, AddPermissionsOptionalParameter addOptionalParameter) {
          return addWithServiceResponseAsync(appId, addOptionalParameter).toBlocking().single().body();
      }
docs: Adds a user to the allowed list of users to access this LUIS application. Users are added using their email address.
  
  @param appId The application ID.
  @param addOptionalParameter the object representing the optional parameters to be set before calling this API
  @throws IllegalArgumentException thrown if parameters fail the validation
  @throws ErrorResponseException thrown if the request is rejected by server
  @throws RuntimeException all other wrapped checked exceptions if the request fails to be sent
  @return the OperationStatus object if successful.