Add email to dropdowns on smarty document manager

functions.php

<?php
add_filter('sp_cdm/admin/fileview/dropdown', function($dropdown){

	
        $arrParts   = explode("</select>", $dropdown);
        foreach($arrParts as &$part){
            if($selPos = strpos($part, "<select")){
                $part = substr($part, 0, $selPos);
            }
        }
       $dropdown  = implode("", $arrParts);	

	
	
	$selected =  sanitize_text_field( cdm_var( 'id' ) );
	$siteusers = get_users(); // you can pass filters and option

	if (count($siteusers) > 0){
		$dropdown .= '<select name="user_uid" id="user_uid" class="user_uid"><option value="">Choose a user</option>';
		foreach ($siteusers as $user) {
			$dropdown .= '<option value="' . $user->ID . '">'.$user->user_nicename . ' ('.$user->user_email .')</option>';
		}
		 $dropdown .= '</select>';
		 $dropdown = str_replace('value="' . $selected . '"','value="' . $selected . '" selected="selected"',  $dropdown);
	}

	
	return $dropdown;
});