ActionGroup.getActionParameterType

Queries the type of the parameter that must be given when activating the named action within action_group.

When activating the action using [gio.action_group.ActionGroup.activateAction], the #GVariant given to that function must be of the type returned by this function.

In the case that this function returns null, you must not give any #GVariant, but null instead.

The parameter type of a particular action will never change but it is possible for an action to be removed and for a new action to be added with the same name but a different parameter type.