protected void preWait() {
    waiting = true;
    DistributionManager mgr = getDistributionManager();
    statStart = mgr.getStats().startReplyWait();
    synchronized (members) {
      Set activeMembers = addListenerAndGetMembers();
      processActiveMembers(activeMembers);
    }
  }
Returns the set of members that this processor should care about.

@return a Set of the current members
@since GemFire 5.7
geode-core/src/main/java/org/apache/geode/distributed/internal/ReplyProcessor21.java