public function __construct() {
            register_activation_hook( __FILE__, array( $this, 'wpldp_rewrite_flush' ) );
            add_action( 'init', array( $this, 'register_site_taxonomy' ), 0 );

            add_action( 'ldp_site_add_form_fields', array( $this, 'add_custom_tax_fields_oncreate_site' ) );