Add Metaboxes using Third Party Plugin

Thank you so much for a well written plugin.
I have spent some time diving into the code and I could not be happier with how the plugin is built. Thank you sharing it!

I have a quick question on how to hook another plugin into adding meta boxes to a section. When I create a profile section class as shown in the code below, what is the exact filter name that would be used to hook into parent::add_meta_boxes?

The section is created like so:

class WP_User_Profile_Workplace_Section extends WP_User_Profile_Section {
	public function add_meta_boxes( $type = '', $user = null ) {
		// Allow third party plugins to add metaboxes
		parent::add_meta_boxes( $type, $user );
                ...
        }
}

If I add any metabox within the add_meta_boxes function above, I can hook into the before or after filters with no problems using something like:
add_action( 'wp_user_workplace_address_metabox_after', 'my_metabox_function', 10, 2 );
I am simply not having any success plugging into parent::add_meta_boxes
Any direction would be greatly appreciated.