public $selfLink; // <link rel='self' type='application/atom+xml'>
public $editLink; // <link rel='edit' type='application/atom+xml'>
public $generator; // ActivityObject representing the generating application
public $selfLink; // <link rel='self' type='application/atom+xml'>
public $editLink; // <link rel='edit' type='application/atom+xml'>
public $generator; // ActivityObject representing the generating application