I like to add a class and an onClick event to a single WordPress menu link.

My code is based on an example given by WordPress here:

    function add_specific_menu_atts( $atts, $item, $args ) {
    $menu_items = array(8071);
    if (in_array($item->ID, $menu_items)) {
        $atts['onClick'] = 'ml('show', 'OUN6T5', true)';
        $atts['class'] = 'ml-onclick-form button';
    }
    return ($atts);
    }
    add_filter( 'nav_menu_link_attributes', 'add_specific_menu_atts', 10, 3 );

It all works fine so far except for the onClick event (a pop-up showing a newsletter form powered by MailerLite).

This is the output I want to achieve:

    <a href="#" onClick="ml('show', 'OUN6T5', true)" class="ml-onclick-form button">Join My Newsletter</a>

But the single quotes in the onClick event are replaced by HTML entites '.

Instead of onClick="ml('show', 'OUN6T5', true)" I get

    onClick="ml('show', 'OUN6T5', true)"

Using html_entity_decode like this didn’t help:

    $atts['onClick'] = html_entity_decode(ml('show', 'OUN6T5', true));

I think that I probably need to apply html_entity_decode to return ($atts);, but I don’t know how to add html_entity_decode to an array.
Maybe I’m also wrong, and another approach would be better. I hope someone can point me into the right direction.