target_contact
Description:
If this channel is for communication with a single contact (that is, TpChannelIface:handle-type is
CONTACT), then a
Contact representing the remote contact.
For chat rooms, contact search channels and other channels without a single remote contact, null.
This is not guaranteed to be set until prepare_async has
finished preparing TP_CHANNEL_FEATURE_CONTACTS; until then, it may be null.