如何显示仅在自定义帖子类型中发布的作者列表？

I'm trying to show a list of authors who have posts in a custom post type. What i've done so far is to use the wp_list_authors which only shows the admin posts and doesn't take into account custom posts. What i really want to do is on my Latest news page which has posts from the custom post, 'News' to just show the authors who have posts in that Custom post type.

If anyone could any light to how i can do this then i would be very appreciative :)

Thanks

    <?php
$blogusers = wp_list_authors();
foreach ( $blogusers as $user ) {
    echo "<li><a href='#' data-option-value='.".strtolower($user->user_login)."'><div class='flag'>".get_avatar($user->ID, 'description', true).'</div>' . $user->user_login ."</a></li>
";    }
?>

I don't think you can do it with this function, but you can do it with direct query, something like

global $wpdb;
$authors=$wpdb->get_results('select `'.$wpdb->prefix.'users`.`ID`, `'.$wpdb->prefix.'users`.`user_login`, `'.$wpdb->prefix.'users`.`display_name` from `'.$wpdb->prefix.'users` inner join `'.$wpdb->prefix.'posts` on `'.$wpdb->prefix.'users`.`ID`=`'.$wpdb->prefix.'posts`.`post_author` where `post_type`=\'news\' group by `'.$wpdb->prefix.'users`.`ID`;');
//you should do a check if $authors is not null and actually got any records returned.
foreach ( $authors as $user ) 
{
    echo "<li><a href='#' data-option-value='".strtolower($user->user_login)."'><div class='flag'>".get_avatar($user->ID, 'description', true).'</div>' . $user->display_name."</a></li>
";    
}