Add d9 support (passes d9 upgrade status check)

cern_integration.info.yml

@@ -4,5 +4,6 @@ package: CERN
 type: module
 version: '8.0.9'
 core: 8.x
+core_version_requirement: ^8 || ^9
 
 required: TRUE

cern_integration.install

@@ -2,9 +2,9 @@
 
 
 function cern_integration_install() {
-  drupal_set_message(t('CERN Integration module installed successfully.'));
+  \Drupal::messenger()->addMessage(t('CERN Integration module installed successfully.'));
 }
 
 function cern_integration_uninstall() {
-  drupal_set_message(t('CERN Integration module was uninstalled successfully.'));
+  \Drupal::messenger()->addMessage(t('CERN Integration module was uninstalled successfully.'));
 }

cern_integration.module

@@ -43,7 +43,7 @@ function cern_integration_update_projects_alter(&$projects)
     // unset($projects['drupal']);
 
     // Remove all centrally managed modules.
-    foreach (system_get_info("module") as $module_name => $module) {
+    foreach (\Drupal::service('extension.list.module')->getExtensionInfo() as $module_name => $module) {
         if (preg_match('#^modules/#', drupal_get_path("module", $module_name))) {
             if (isset($module["project"])){
                 unset($projects[$module["project"]]);
@@ -52,7 +52,7 @@ function cern_integration_update_projects_alter(&$projects)
     }
 
     // Remove all centrally managed themes.
-    foreach (system_get_info("theme") as $theme_name => $theme) {
+    foreach (\Drupal::service('extension.list.theme')->getExtensionInfo() as $theme_name => $theme) {
         if (preg_match('#^themes/#', drupal_get_path("theme", $theme_name))) {
             if (isset($theme["project"])){
                 unset($projects[$theme["project"]]);
@@ -91,7 +91,7 @@ function cern_integration_form_views_form_user_admin_people_page_1_alter(&$form,
 *  Disable fields under admin/people/create
 */
 function cern_integration_form_user_register_form_alter(&$form, &$form_state, $form_id){
-    drupal_set_message(t("Adding/Removing users is DISABLED."),"warning");
+    \Drupal::messenger()->addMessage(t("Adding/Removing users is DISABLED."),"warning");
     // Disable all elements from this form.
     foreach (\Drupal\Core\Render\Element::children($form) as $key) {
         $form[$key]['#disabled'] = TRUE;

src/Controller/BackendController.php

@@ -13,7 +13,7 @@ class BackendController extends ControllerBase {
   /**
    * Returns a render-able array for a test page.
    */
-  public function redirect() {
+  public function redirect($route_name, array $route_parameters = [], array $options = [], $status = 302) {
      return new RedirectResponse("/_site");
   }