get_parameter_type

Queries the type of the parameter that must be given when activating this.

When activating the action using [method@Gio.Action.activate], the [type@GLib.Variant] 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 [type@GLib.Variant], but `NULL` instead.

Parameters:

this	a [type@Gio.Action]

Returns:

the parameter type