‘_vala_dbus_register_object’ defined but not used

In building libgwibber I get the compiler warnings below, from the generated code.

service.c:223: warning: ‘_vala_dbus_register_object’ defined but not used
  CC libgwibber_la-accounts.lo
accounts.c: In function ‘_dbus_handle_accounts_interface_updated’:
accounts.c:819: warning: unused variable ‘reply’
accounts.c: In function ‘_dbus_handle_accounts_interface_created’:
accounts.c:836: warning: unused variable ‘reply’
accounts.c: In function ‘_dbus_handle_accounts_interface_deleted’:
accounts.c:853: warning: unused variable ‘reply’
accounts.c: At top level:
accounts.c:189: warning: ‘_vala_dbus_register_object’ defined but not used
  CC libgwibber_la-urlshorten.lo
urlshorten.c:150: warning: ‘_vala_dbus_register_object’ defined but not used
  CC libgwibber_la-connection.lo
connection.c: In function ‘_dbus_handle_connection_interface_connection_offline’:
connection.c:480: warning: unused variable ‘reply’
connection.c: In function ‘_dbus_handle_connection_interface_connection_online’:
connection.c:491: warning: unused variable ‘reply’
connection.c: At top level:
connection.c:157: warning: ‘_vala_dbus_register_object’ defined but not used
  CC libgwibber_la-streams.lo
streams.c:149: warning: ‘_vala_dbus_register_object’ defined but not used