public function get_installed_version() {
		if ( $this->is_installable() && $this->is_installed() ) {
			$type = $this->get( 'type' );
			if ( 'plugin' === $type ) {
				$data = get_plugin_data( trailingslashit( WP_PLUGIN_DIR ) . $this->get( 'update_file' ) );
				return $data['Version'];
			} elseif ( 'theme' === $type ) {
				$data = wp_get_theme( $this->get( 'update_file' ) );
				return $data->get( 'Version' );
			}
		}
		return '';
	}