D-Bus interface is not registered

Attached is sample code that creates a simple DBus server that replies to ping and a client to test it with. The service gets registered and shows up in the session bus but it won't work. Running with QDBUS_DEBUG=1 shows that the queries are received but the replies are error messages claiming that the interface is unknown. Qt5's documentation claims that the interface needs to be specified with Q_CLASSINFO. The server class does that but still it does not show up. The D-Feet inspection tool says the same thing.

You can call the DBus methods provided by default (such as peer ping and introspection) when the server is running and they work.

To test the application, just compile the code and then run dbusserver and while it is running run dbusclient. On success dbusclient should print how many times the ping function has been called. Currently it will always print an error.