Futures returned by CommandDispatcher.submitOnCluster(...) throw ClassCastException on get() if target node has no corresponding CommandDispatcher

The futures returned by CommandDispatcher.submitOnCluster(...) contain the command execution results per member of the cluster. However, if a given member has no active CommandDispatcher to receive the command, the resulting behavior is not handled, and the Future.get() will throw a ClassCastException. This is because the RspFilter contained in the RspOptions as passed to the MessageDispatcher is not invoked for unicast requests.

The API will likely need to be adjusted/documented to define what behavior to expect in this scenario.