c_g_dbus_method_invocation_return_dbus_error

Undocumented in source but is binding to C. You might be able to learn more by searching the web for its name.
__gshared extern (C)
void function(GDBusMethodInvocation* invocation, gchar* errorName, gchar* errorMessage) c_g_dbus_method_invocation_return_dbus_error;

Meta