Topology updates of EJBClient ClusterContexts not being processed correctly after failover

ClusterContexts are used by EJBClient to keep track of the current set of nodes in a cluster, so that if an EJBClient invocation fails on one node, it may failover to another node in the same cluster. The ClusterContext is made up of ClusterNodeManagers which are responsible for setting up the connections between the EJBClient and the nodes in the cluster.

Cluster topology updates are sent to registered EJBClients whenever the cluster topology changes (nodes join, nodes leave a cluster). Thse topology updates are processed on the client side by ClusterTopologyUpdateHandler and are used to update the current contents of the associated ClusterContext held on the client.

The current implementation of the handling of topology updates does not correctly handle the addition/removal of ClusterNodeManagers from the cluster context - namely, rather than check whether or not a new ClusterNodeManager really needs to be added, ClusterNodeManagers are added for every node in the received topology update, leading to many unnecessary EJBReceivers and their channels being created.

The logs show that up to 18 cluster node manager instances may be created, have their EJBReceivers registered and channels to the remote node created, when only one node has been added to the cluster.