code: public Observable<ServiceResponse<OperationStatus>> addWithServiceResponseAsync(UUID appId, AddPermissionsOptionalParameter addOptionalParameter) {
          if (this.client.endpoint() == null) {
              throw new IllegalArgumentException("Parameter this.client.endpoint() is required and cannot be null.");
          }
          if (appId == null) {
              throw new IllegalArgumentException("Parameter appId is required and cannot be null.");
          }
          final String email = addOptionalParameter != null ? addOptionalParameter.email() : null;
  
          return addWithServiceResponseAsync(appId, email);
      }
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
  @return the observable to the OperationStatus object