WordPress: Bootstrap 4 Gallery (Filter default gallery)

/**
 *  Bootstrap 4 gallery
 *  Base galeria padrão / Default gallery: https://core.trac.wordpress.org/browser/trunk/src/wp-includes/media.php#L1677
*/
add_filter( 'post_gallery', 'wpmidia_bootstrap_gallery', 10, 2);
function wpmidia_bootstrap_gallery( $output = '', $atts ) {

    if (strlen($atts['columns']) < 1) $columns = 3;
    else $columns = $atts['columns'];
    $images = explode(',', $atts['ids']);

    if ( $columns < 1 || $columns > 12 ) $columns == 3;

    $col_class = 'col-lg-' . 12/$columns;

    $output = '<div class="row text-center text-lg-left gallery">';
    $i = 0;

    foreach ( $images as $key => $value ) {

        $image_attributes = wp_get_attachment_image_src( $value, 'full'); //"Full" para o responsivo :)
        $output .= '
            <div class="'.$col_class.'">
              <a data-gallery="gallery" href="'.esc_url($image_attributes[0]).'" class="d-block mb-4 h-100">
                    <img src="'.esc_url($image_attributes[0]).'" alt="" class="img-fluid img-thumbnail">
                </a>
            </div>';
        $i++;
    }

    $output .= '</div>';

    return $output;
}