connectionMonitor in RestProtocol seems not work

[turnin]

• I have searched the issues of this repository and believe that this is not a duplicate.
• I have checked the FAQ of this repository and believe that this is not a duplicate.

Environment

• Dubbo version: 2.6.5

Confusion

the code below create a connectionMonitor instance, but Start method seems not called

@Override
    protected <T> T doRefer(Class<T> serviceType, URL url) throws RpcException {
        if (connectionMonitor == null) {
            connectionMonitor = new ConnectionMonitor();
        }
      ...
    }

[beiwei30]

looks like a bug, would you mind to fix it?