JRMPInvokerProxyHA should not fail over if java.rmi.UnmarshalException is caught

JRMPInvokerProxyHA will allow a failover if the invocation throws a java.rmi.UnmarshalException. This is invalid, as there is no way to know if the exception is due to a problem on the server side (i.e. before the invocation was handled by the Invoker) or on the client side (when unmarshalling a response).

Per the UnmarshalException javadoc:

An UnmarshalException can be thrown while unmarshalling the parameters or results of a remote method call if any of the following conditions occur:

• if an exception occurs while unmarshalling the call header
• if the protocol for the return value is invalid
• if a java.io.IOException occurs unmarshalling parameters (on the server side) or the return value (on the client side).
• if a java.lang.ClassNotFoundException occurs during unmarshalling parameters or return values
• if no skeleton can be loaded on the server-side; note that skeletons are required in the 1.1 stub protocol, but not in the 1.2 stub protocol.
• if the method hash is invalid (i.e., missing method).
• if there is a failure to create a remote reference object for a remote object's stub when it is unmarshalled.