code: @Override
      protected final void checkIntegrity () throws InternetSCSIException {
  
          String exceptionMessage;
  
          do {
              if (reasonCode != ReasonCode.PROTOCOL_ERROR && dataSequenceNumber != 0) {
                  exceptionMessage = "The DataSN/R2TSN is only valid, if the reason code is a 'Protocol Error'.";
                  break;
              }
  
              // message is checked correctly
              return;
          } while (false);
  
          throw new InternetSCSIException(exceptionMessage);
      }
docs: {@inheritDoc}