Issue #3091584 by tcrawf: Support language on member updates

Closes #3091584

mailchimp.module

@@ -575,7 +575,7 @@ function mailchimp_addto_queue($function, array $args) {
  *
  * @see Mailchimp_Lists::updateMember()
  */
-function mailchimp_update_member($list_id, $email, $merge_vars, $interests = [], $format = 'html', $double_optin = FALSE, $gdpr_consent = FALSE) {
+function mailchimp_update_member($list_id, $email, $merge_vars, $interests = [], $format = 'html', $double_optin = FALSE, $language = NULL, $gdpr_consent = FALSE) {
   $config = \Drupal::config('mailchimp.settings');
 
   if ($config->get('cron')) {
@@ -589,10 +589,14 @@ function mailchimp_update_member($list_id, $email, $merge_vars, $interests = [],
       'gdpr_consent' => $gdpr_consent,
     ];
 
+    if ($language) {
+      $args['language'] = $language;
+    }
+
     return mailchimp_addto_queue('mailchimp_update_member_process', $args);
   }
 
-  return mailchimp_update_member_process($list_id, $email, $merge_vars, $interests, $format, $double_optin, $gdpr_consent);
+  return mailchimp_update_member_process($list_id, $email, $merge_vars, $interests, $format, $double_optin, $language, $gdpr_consent);
 }
 
 /**
@@ -600,7 +604,7 @@ function mailchimp_update_member($list_id, $email, $merge_vars, $interests = [],
  *
  * @see Mailchimp_Lists::updateMember()
  */
-function mailchimp_update_member_process($list_id, $email, $merge_vars, $interests, $format, $double_optin = FALSE, $gdpr_consent = FALSE) {
+function mailchimp_update_member_process($list_id, $email, $merge_vars, $interests, $format, $double_optin = FALSE, $language = NULL, $gdpr_consent = FALSE) {
   $result = FALSE;
 
   try {
@@ -626,6 +630,11 @@ function mailchimp_update_member_process($list_id, $email, $merge_vars, $interes
       }
     }
 
+    // Set language.
+    if ($language) {
+      $parameters['language'] = $language;
+    }
+
     // Set merge fields.
     if (!empty($merge_vars)) {
       $parameters['merge_fields'] = (object) $merge_vars;
@@ -672,7 +681,7 @@ function mailchimp_update_member_process($list_id, $email, $merge_vars, $interes
         'list' => $list_id,
       ]);
 
-      return mailchimp_update_member_process($list_id, $email, $merge_vars, $interests, $format, TRUE, $gdpr_consent);
+      return mailchimp_update_member_process($list_id, $email, $merge_vars, $interests, $format, TRUE, $language, $gdpr_consent);
     }
 
     \Drupal::logger('mailchimp')->error('An error occurred updating {email} on list {list}. "{message}"', [