Issue #2722265 by willito, kellyimagined, joachim, hussainweb, munizjor,...

Issue #2722265 by willito, kellyimagined, joachim, hussainweb, munizjor, selfuntitled, lisa.ugray, soulsesa, The Sean, kjl16, kurthill4: docs for MailManager::mail() refer to obsolete function user_preferred_langcode()

core/lib/Drupal/Core/Mail/MailManagerInterface.php

@@ -23,10 +23,11 @@ interface MailManagerInterface extends PluginManagerInterface {
    *
    * Finding out what language to send the email with needs some consideration.
    * If you send email to a user, her preferred language should be fine, so use
-   * user_preferred_langcode(). If you send email based on form values filled on
-   * the page, there are two additional choices if you are not sending the email
-   * to a user on the site. You can either use the language used to generate the
-   * page or the site default language. See
+   * \Drupal\Core\Session\AccountInterface::getPreferredAdminLangcode(). If you
+   * send email based on form values filled on the page, there are two
+   * additional choices if you are not sending the email to a user on the site.
+   * You can either use the language used to generate the page or the site
+   * default language. See
    * Drupal\Core\Language\LanguageManagerInterface::getDefaultLanguage(). The
    * former is good if sending email to the person filling the form, the later
    * is good if you send email to an address previously set up (like contact
@@ -46,7 +47,7 @@ interface MailManagerInterface extends PluginManagerInterface {
    *       $params['account'] = $account;
    *       // example_mail() will be called based on the first
    *       // MailManagerInterface->mail() parameter.
-   *       \Drupal::service('plugin.manager.mail')->mail('example', 'notice', $account->mail, user_preferred_langcode($account), $params);
+   *       \Drupal::service('plugin.manager.mail')->mail('example', 'notice', $account->mail, $langcode, $params);
    *     }
    *   }
    *