Program: 87043
Project: 87043
Buggy source:
private void handleGossipMessage(GossipMessage message){
  if (shuttingDown) {
    return;
  }
  String senderKey=MemberKey.getKey(message);
  boolean updateTags=false;
  for (int i=0; i < message.getMembers().size(); ++i) {
    String key=message.getMembers().get(i);
    Member m=memberHolder.getMember(key);
    if (m == null) {
      String protocol=Parameters.INSTANCE.getProperty(PROTOCOL_PROPERTY,DEFAULT_PROTOCOL);
      if (protocol.equalsIgnoreCase("String_Node_Str")) {
        if (LOG.isTraceEnabled()) {
          LOG.trace(new StringBuilder().append(MemberKey.getKey(me)).append("String_Node_Str").append(message.getIp()).append("String_Node_Str").append(message.getGossipPort()).append("String_Node_Str").append(message.getDataPort()).toString());
        }
        m=new RemoteMemberUDP(memberHolder);
      }
 else {
        if (LOG.isTraceEnabled()) {
          LOG.trace(new StringBuilder().append(MemberKey.getKey(me)).append("String_Node_Str").append(message.getIp()).append("String_Node_Str").append(message.getGossipPort()).append("String_Node_Str").append(message.getDataPort()).toString());
        }
        m=new RemoteMemberTCP(memberHolder);
      }
      String[] values=key.split("String_Node_Str");
      m.setIp(values[0]);
      m.setGossipPort(Integer.parseInt(values[1]));
      m.setDataPort(Integer.parseInt(values[2]));
      ((AbstractMember)m).initialize();
    }
    memberHolder.updateMemberStatus(m);
    int memberClock=message.getClock().get(i);
    int knownMemberClock=m.getSequence().get();
    if (memberClock > knownMemberClock) {
      if (key.equals(senderKey)) {
        updateTags=true;
      }
      m.getSequence().set(memberClock);
      List<String> topics=message.getListeners().get(key);
      if (topics == null) {
        topics=Collections.emptyList();
      }
      List<Registration> toRemove=new ArrayList<>();
      for (      Registration reg : registry.getAllRegistrations()) {
        if (reg.getMember().equals(m)) {
          if (!topics.contains(TopicUtils.getTopicString(reg.getTopic(),reg.getPartition().pattern()))) {
            toRemove.add(reg);
          }
        }
      }
      registry.removeRegistrations(toRemove);
      for (      String topicString : topics) {
        String topic=TopicUtils.getTopic(topicString);
        String partition=TopicUtils.getPartition(topicString);
        if (!registry.getRegisteredMembers(topic).contains(m)) {
          registry.registerMemberForTopic(topic,partition,m);
        }
      }
    }
  }
  if (updateTags) {
    Member m=memberHolder.getMember(senderKey);
    m.getTags().clear();
    m.getTags().putAll(message.getTags());
  }
}

Fixed version (ground truth):
private void handleGossipMessage(GossipMessage message){
  if (shuttingDown) {
    return;
  }
  String senderKey=MemberKey.getKey(message);
  boolean updateTags=false;
  for (int i=0; i < message.getMembers().size(); ++i) {
    String key=message.getMembers().get(i);
    Member m=memberHolder.getMember(key);
    if (m == null) {
      String protocol=Parameters.INSTANCE.getProperty(PROTOCOL_PROPERTY,DEFAULT_PROTOCOL);
      if (protocol.equalsIgnoreCase("String_Node_Str")) {
        if (LOG.isTraceEnabled()) {
          LOG.trace(new StringBuilder().append(MemberKey.getKey(me)).append("String_Node_Str").append(message.getIp()).append("String_Node_Str").append(message.getGossipPort()).append("String_Node_Str").append(message.getDataPort()).toString());
        }
        m=new RemoteMemberUDP(memberHolder);
      }
 else {
        if (LOG.isTraceEnabled()) {
          LOG.trace(new StringBuilder().append(MemberKey.getKey(me)).append("String_Node_Str").append(message.getIp()).append("String_Node_Str").append(message.getGossipPort()).append("String_Node_Str").append(message.getDataPort()).toString());
        }
        m=new RemoteMemberTCP(memberHolder);
      }
      String[] values=key.split("String_Node_Str");
      m.setIp(values[0]);
      m.setGossipPort(Integer.parseInt(values[1]));
      m.setDataPort(Integer.parseInt(values[2]));
      ((AbstractMember)m).initialize();
    }
    memberHolder.updateMemberStatus(m);
    int memberClock=message.getClock().get(i);
    int knownMemberClock=m.getSequence().get();
    if (memberClock > knownMemberClock) {
      if (key.equals(senderKey)) {
        updateTags=true;
      }
      m.getSequence().set(memberClock);
      List<String> topics=message.getListeners().get(key);
      if (topics == null) {
        topics=Collections.emptyList();
      }
      List<Registration> toRemove=new ArrayList<>();
      for (      Registration reg : registry.getAllRegistrations()) {
        if (reg.getMember().equals(m)) {
          if (!topics.contains(TopicUtils.getTopicString(reg.getTopic(),reg.getPartition()))) {
            toRemove.add(reg);
          }
        }
      }
      registry.removeRegistrations(toRemove);
      for (      String topicString : topics) {
        String topic=TopicUtils.getTopic(topicString);
        String partition=TopicUtils.getPartition(topicString);
        if (!registry.getRegisteredMembers(topic).contains(m)) {
          registry.registerMemberForTopic(topic,partition,m);
        }
      }
    }
  }
  if (updateTags) {
    Member m=memberHolder.getMember(senderKey);
    m.getTags().clear();
    m.getTags().putAll(message.getTags());
  }
}