WordPress Version: 5.4
/**
* Returns a list of meta keys to be (maybe) populated in wp_update_user().
*
* The list of keys returned via this function are dependent on the presence
* of those keys in the user meta data to be set.
*
* @since 3.3.0
* @access private
*
* @param WP_User $user WP_User instance.
* @return string[] List of user keys to be populated in wp_update_user().
*/
function _get_additional_user_keys($user)
{
$keys = array('first_name', 'last_name', 'nickname', 'description', 'rich_editing', 'syntax_highlighting', 'comment_shortcuts', 'admin_color', 'use_ssl', 'show_admin_bar_front', 'locale');
return array_merge($keys, array_keys(wp_get_user_contact_methods($user)));
}