@Override
  public synchronized void nodeJoined(GfManagerAgent source, GemFireVM joined) {
    noteNewMember(joined);

    InetAddress hostIpAddress = joined.getHost();

    GemFireHealthConfig config = (GemFireHealthConfig) hostConfigs.get(hostIpAddress);
    if (config == null) {
      config = getDefaultGemFireHealthConfig();
    }
    joined.addHealthListener(this, config);
  }
Makes note of the newly-joined member
geode-core/src/main/java/org/apache/geode/admin/internal/GemFireHealthImpl.java