@Override
  protected void process(ClusterDistributionManager dm) {

    if (interfaces == null || interfaces.size() == 0) {
      // this.rejectionMessage = "Peer " + getSender() + " has no network interfaces";
    } else {
      dm.setEquivalentHosts(interfaces);
    }
    dm.setDistributedSystemId(distributedSystemId);
    dm.setRedundancyZone(getSender(), redundancyZone);

    // Process the registration of instantiators & log failures, if any.
    if (fromDataProblems != null) {
      if (logger.isDebugEnabled()) {
        logger.debug(fromDataProblems);
      }
    }

    if (serializerIds != null) {
      for (int i = 0; i < serializerIds.length; i++) {
        String cName = serializerClasseNames[i];
        if (cName != null) {
          InternalDataSerializer.register(cName, false, null, null, serializerIds[i]);
        }
      }
    }

    if (instantiatorIds != null) {
      // Process the Instantiator registrations.
      for (int i = 0; i < instantiatorIds.length; i++) {
        String instantiatorClassName = instantiatorClasseNames[i];
        String instantiatedClassName = instantiatedClasseNames[i];
        int id = instantiatorIds[i];
        if ((instantiatorClassName != null) && (instantiatedClassName != null)) {
          InternalInstantiator.register(instantiatorClassName, instantiatedClassName, id, false);
        }
      }
    }

    dm.processStartupResponse(sender, rejectionMessage);

    StartupMessageReplyProcessor proc =
        (StartupMessageReplyProcessor) ReplyProcessor21.getProcessor(processorId);
    if (proc != null) {
      if (rejectionMessage != null) {
        // there's no reason to wait for other responses
        proc.setReceivedRejectionMessage(true);
      } else {
        if (!responderIsAdmin) {
          proc.setReceivedAcceptance(true);
        }
      }

      proc.process(this);
      if (logger.isTraceEnabled(LogMarker.DM_VERBOSE)) {
        logger.trace(LogMarker.DM_VERBOSE, "{} Processed {}", proc, this);
      }
    } // proc != null
  }
Adds the distribution managers that have started up to the current DM's list of members.

This method is invoked on the receiver side
geode-core/src/main/java/org/apache/geode/distributed/internal/StartupResponseMessage.java