code: public Observable<Boolean> checkNameExistsAsync(String accountName) {
          return checkNameExistsWithServiceResponseAsync(accountName).map(new Func1<ServiceResponse<Boolean>, Boolean>() {
              @Override
              public Boolean call(ServiceResponse<Boolean> response) {
                  return response.body();
              }
          });
      }
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