code: public Observable<ServiceResponse<Boolean>> checkNameExistsWithServiceResponseAsync(String accountName) {
          if (accountName == null) {
              throw new IllegalArgumentException("Parameter accountName is required and cannot be null.");
          }
          if (this.client.apiVersion() == null) {
              throw new IllegalArgumentException("Parameter this.client.apiVersion() is required and cannot be null.");
          }
          return service.checkNameExists(accountName, this.client.apiVersion(), this.client.acceptLanguage(), this.client.userAgent())
              .flatMap(new Func1<Response<Void>, Observable<ServiceResponse<Boolean>>>() {
                  @Override
                  public Observable<ServiceResponse<Boolean>> call(Response<Void> response) {
                      try {
                          ServiceResponse<Boolean> clientResponse = checkNameExistsDelegate(response);
                          return Observable.just(clientResponse);
                      } catch (Throwable t) {
                          return Observable.error(t);
                      }
                  }
              });
      }
docs: Checks that the Azure Cosmos DB account name already exists. A valid account name may contain only lowercase letters, numbers, and the '-' character, and must be between 3 and 50 characters.
  
  @param accountName Cosmos DB database account name.
  @throws IllegalArgumentException thrown if parameters fail the validation
  @return the observable to the Boolean object