Apply fix to applies and build in the builder to add route context to cache

Closes #3495164

src/MenuBasedBreadcrumbBuilder.php

@@ -6,6 +6,7 @@ use Drupal\Component\Utility\SortArray;
 use Drupal\Core\Breadcrumb\Breadcrumb;
 use Drupal\Core\Breadcrumb\BreadcrumbBuilderInterface;
 use Drupal\Core\Cache\CacheBackendInterface;
+use Drupal\Core\Cache\CacheableMetadata;
 use Drupal\Core\Config\ConfigFactoryInterface;
 use Drupal\Core\Controller\TitleResolverInterface;
 use Drupal\Core\Entity\EntityTypeManagerInterface;
@@ -169,7 +170,11 @@ class MenuBasedBreadcrumbBuilder implements BreadcrumbBuilderInterface {
   /**
    * {@inheritdoc}
    */
-  public function applies(RouteMatchInterface $route_match) {
+  public function applies(RouteMatchInterface $route_match, ?CacheableMetadata $cacheable_metadata = NULL) {
+    // @todo Remove null safe operator in Drupal 12.0.0, see
+    //   https://www.drupal.org/project/drupal/issues/3459277.
+    $cacheable_metadata?->addCacheContexts(['route']);
+
     // This may look heavyweight for applies() but we have to check all ways the
     // current path could be attached to the selected menus before turning over
     // breadcrumb building (and caching) to another builder.  Generally this
@@ -292,6 +297,10 @@ class MenuBasedBreadcrumbBuilder implements BreadcrumbBuilderInterface {
       $breadcrumb->addCacheContexts(['languages:language_content']);
     }
 
+    // @todo Remove in Drupal 12.0.0, will be added from ::applies(). See
+    //   https://www.drupal.org/project/drupal/issues/3459277
+    $breadcrumb->addCacheContexts(['route']);
+
     // Changing the <front> page will invalidate any breadcrumb generated here:
     $site_config = $this->configFactory->get('system.site');
     $breadcrumb->addCacheableDependency($site_config);