title: Multiple user role to a custom post type
body: <p>I've created a CPT, issue_chapter, and a new user translator. Now how a dropdown can be added with list of translators in this CPT? &quot;Author&quot; and &quot;Translator&quot; both should be there.</p>
  <p>I have created a metabox</p>
  <pre><code>add_meta_box( 
          'translator', 
          'Translator', 
          'zc_translator_meta_box_callback', 
          'issue_chapter', 
          'advanced', 
          'high' );
  
  function zc_translator_meta_box_callback( $post ) {
  $role = 'translator';
  
  $query_users_ids_by_role = array(
      'field' =&gt; 'id',
      'role' =&gt; $role
  );
  
  $array_of_users_ids = get_users( $query_users_ids_by_role );
  
  $users_ids_list = implode( ',',$array_of_users_ids );
  
  $query_for_dropdown = array(
      'include' =&gt; $user_ids_list,
  );
  
  wp_dropdown_users( $query_for_dropdown );
  }
  </code></pre>
  <p>Now how to save the value?
  Thank you.</p>