hook_mail_alter() missing components in doc

The documentation appears to leave out 2 keys in the $message array: 'params' and 'language'.

The following is an excerpt from the drupal_mail function, showing that these two variables are included in the array passed to hook_mail_alter.

// Bundle up the variables into a structured array for altering.
  $message = array(
    'id'       => $module .'_'. $key,
    'to'       => $to,
    'from'     => isset($from) ? $from : $default_from,
    'language' => $language,
    'params'   => $params,
    'subject'  => '',
    'body'     => array()
  );