public static void addReconnectListener(ReconnectListener listener) {
    synchronized (existingSystemsLock) {
      synchronized (reconnectListeners) {
        reconnectListeners.add(listener);
      }
    }
  }
Makes note of a <code>ReconnectListener</code> whose <code>onReconnect</code> method will be
invoked when a connection is recreated to a distributed system during auto-reconnect.
<p>
The ReconnectListener set is cleared after a disconnect.
geode-core/src/main/java/org/apache/geode/distributed/internal/InternalDistributedSystem.java