Add class name from CPT taxonomies name

Hi,

I add [display-posts wrapper=”ul” wrapper_class=”js-filter uk-child-width-1-4 uk-child-width-1-4m uk-text-center”] and I want to add custom classes to li elements. The classes shoud be a name form cpt taxonomies.
Now I add some code into core file to make it and it’s works but this metod is a bad..
In plugin below line 586 a add some code:

    $terms = get_the_terms(get_the_ID(), 'portfolio_category');
    $class = [];
    foreach ($terms as $term) {
        $class[] = $term->slug;
    }
    $class[]='listing-item';

    /**
     * Filter the post classes for the inner wrapper element of the current post.
     *
     * @since 2.2
     *
     * @param array    $class         Post classes.
     * @param WP_Post  $post          Post object.
     * @param WP_Query $dps_listing       WP_Query object for the posts listing.
     * @param array    $original_atts Original attributes passed to the shortcode.
     */
    $class  = array_map('sanitize_html_class', apply_filters('display_posts_shortcode_post_class', $class, $post, $dps_listing, $original_atts));
    $output = '<' . $inner_wrapper . ' class="' . implode(' ', $class) . '">' . $image . $title . $date . $author . $category_display_text . $excerpt . $content . '</' . $inner_wrapper . '>';

In front I have something like this:

<ul class="js-filter uk-child-width-1-4 uk-child-width-1-4m uk-text-center"><li class="identyfikacje-wizualne listing-item"><a......etc. 

How I can do this by functions.php?