@Override
    protected void processActiveMembers(Set activeMembers) {
      super.processActiveMembers(activeMembers);
      if (!activeMembers.contains(targetMember)) {
        targetMemberHasLeft = true;
      }
    }
process the failure set from sending the message
geode-core/src/main/java/org/apache/geode/internal/cache/StateFlushOperation.java