@Override
    public void messageReceived(Message<InternalDistributedMember> msg)
        throws MemberShunnedException {
      membership.processMessage(msg);

    }
Don't provide events until the caller has told us we are ready.

Synchronization provided via GroupMembershipService.class.

Note that in practice we only need to delay accepting the first client; we don't need to put
this check before every call...
geode-core/src/main/java/org/apache/geode/distributed/internal/DistributionImpl.java