// Make sure we can decode it.
RPCRequest decoded = RPC.decodeRequest(request);
Object deserializedArg = decoded.getParameters()[0];
assertEquals(Arg.class, deserializedArg.getClass());
IsSerializable thing = ((Arg) deserializedArg).handle.thing.any;
TypedHandle handle = (TypedHandle) thing;
assertEquals(123, handle.thing);
}