docs: public Channel addOrderer(Orderer orderer) throws InvalidArgumentException {
  
          if (shutdown) {
              throw new InvalidArgumentException(format("Channel %s has been shutdown.", name));
          }
  
          if (null == orderer) {
              throw new InvalidArgumentException("Orderer is invalid can not be null.");
          }
  
          logger.debug(format("Channel %s adding %s", toString(), orderer.toString()));
  
          orderer.setChannel(this);
          ordererEndpointMap.put(orderer.getEndpoint(), orderer);
          orderers.add(orderer);
          return this;
      }