protected function locate_configuration_file() {

		$located = '';

		// By default, search only in the plugin folder.
		$folders = array( dirname( $this->get_plugin( 'fullpath' ) ) );

		/**
		 * Filter to modify the array of configuration folders.
		 *
		 * @since 2.0.0
		 *
		 * @param string[] $folders The array of folders.
		 */
		$folders = (array) apply_filters( 'wp_requirements_configuration_folders', $folders );

		foreach ( $folders as $folder ) {
			$path = trailingslashit( $folder ) . self::CONFIG_FILE_NAME;
			if ( is_readable( $path ) ) {
				$located = $path;
				break;
			}
		}

		return $located;
	}