code: private static void validateResponse(final Command response) throws NegativeResponseException {
          if (response.getCommandStatus() != SMPPConstant.STAT_ESME_ROK) {
              throw new NegativeResponseException(response.getCommandStatus());
          }
      }
docs: Validate the response, the command_status should be 0 otherwise will
  throw {@link NegativeResponseException}.
  
  @param response is the response.
  @throws NegativeResponseException if the command_status value is not zero.