HornetQConnectionFactory has a default ctor for serialization but to be usable it must have set either its discovery address + ports or its static connectors using setStaticConnectors() method.
If you want to set a single connector you must:
create a Pair with your connector config (and null if there is no backup), add it a list and pass the list to setStaticConnectors().
hope that helps
Take a look at the usermanual and examples to see how ton create a connection factory using a TransportConfiguration.