public function add_endpoint( $endpoint = '', $endpoint_type = \EP_ROOT, $callback = array() ) {
		if ( ! isset( $this->rewrite_endpoint[ $endpoint ] ) ) {
			$this->rewrite_endpoint[ $endpoint ] = array(
				'type'     => $endpoint_type,
				'callback' => $callback,
			);
		}
		return $this;
	}