docs: ManagerEvent addMember(BridgeEnterEvent event)
      {
          List<BridgeEnterEvent> remaining = null;
  
          synchronized (members)
          {
              if (members.put(event.getChannel(), event) == null
                      && members.size() == 2)
              {
                  remaining = new ArrayList<>(members.values());
              }
          }
  
          if (remaining == null)
          {
              return null;
          }
  
          logger.info("Members size " + remaining.size() + " " + event);
  
          BridgeEvent bridgeEvent = buildBridgeEvent(
                  BridgeEvent.BRIDGE_STATE_LINK,
                  remaining);
  
          logger.info("Bridge " + bridgeEvent.getChannel1() + " " + bridgeEvent.getChannel2());
  
          return bridgeEvent;
      }