Original Empathy bug report: https://bugzilla.gnome.org/show_bug.cgi?id=602328

To reproduce:
- start a chat with a contact using Empathy and launch dbus-monitor
- start typing in the chat window: GetContactAttributes () is called
- wait a bit that Empathy's typing timer times out: GetContactAttributes () is called again
- start typing again: GetContactAttributes () is called
- etc.

That's because each time the ChatStateChanged signal is fired, Empathy calls tp_connection_get_contacts_by_handle() to get the TpContact object associated with the signal. As Empathy already keep a ref on this TpContact, tp-glib is supposed to return the existing contact object (which it does, pointers are the same) but it still makes a call to GetContactAttributes ().
It shouldn't call this function when re-using an existing contact object as this leads to useless D-Bus round trips.

Note that if you are using a released Empathy version, you'll see 2 calls of GetContactAttributes(). That's because Empathy was handling the ChatStateChanged twice. This has been fixed in master and gnome-2.28.