A client can connect to multiple members and also to a member using multiple connections. On a node you can query a client using `ClientEngineImpl.getEndpoints(uuid)`. But if a client has no connection to a member then that method will return nothing.

But I feel like sending an operation like ResolveClientOperation to all members just to find a monitoring info is over-engineering. 
I think you can return a dummy endpoint like unidentified-client-endpoint...