Method addIncludePath

/**
 * Add a directory where HTMLHelper should search for helpers. You may
 * either pass a string or an array of directories.
 *
 * @param   string  $path  A path to search.
 *
 * @return  array  An array with directory elements
 *
 * @since       1.5
 * @deprecated  5.0 Use the service registry instead
 */
public static function addIncludePath($path = '')
{
    @trigger_error('Support for registering lookup paths is deprecated and will be removed in Joomla 5.0, use the service registry instead', E_USER_DEPRECATED);
    // Loop through the path directories
    foreach ((array) $path as $dir) {
        if (!empty($dir) && !\in_array($dir, static::$includePaths)) {
            array_unshift(static::$includePaths, Path::clean($dir));
        }
    }
    return static::$includePaths;
}