Issue #2237241 by pwolanin: BreadcrumbManager does not have a proper interface .

core/lib/Drupal/Core/Breadcrumb/BreadcrumbBuilderInterface.php

@@ -31,7 +31,7 @@ public function applies(array $attributes);
    *   Attributes representing the current page.
    *
    * @return array
-   *   A render array for the breadcrumbs. Returning an empty array will
+   *   An array of HTML links for the breadcrumb. Returning an empty array will
    *   suppress all breadcrumbs.
    */
   public function build(array $attributes);

core/lib/Drupal/Core/Breadcrumb/BreadcrumbManager.php

@@ -13,11 +13,14 @@
 /**
  * Provides a breadcrumb manager.
  *
- * Can be assigned any number of other BreadcrumbBuilderInterface objects
- * by calling the addBuilder() method, then uses the highest priority one
- * to build breadcrumbs when build() is called.
+ * Can be assigned any number of BreadcrumbBuilderInterface objects by calling
+ * the addBuilder() method. When build() is called it iterates over the objects
+ * in priority order and uses the first one that returns TRUE from
+ * BreadcrumbBuilderInterface::applies() to build the breadcrumbs.
+ *
+ * @see \Drupal\Core\DependencyInjection\Compiler\RegisterBreadcrumbBuilderPass
  */
-class BreadcrumbManager implements BreadcrumbBuilderInterface {
+class BreadcrumbManager implements ChainBreadcrumbBuilderInterface {
 
   /**
    * The module handler to invoke the alter hook.
@@ -53,12 +56,7 @@ public function __construct(ModuleHandlerInterface $module_handler) {
   }
 
   /**
-   * Adds another breadcrumb builder.
-   *
-   * @param \Drupal\Core\Breadcrumb\BreadcrumbBuilderInterface $builder
-   *   The breadcrumb builder to add.
-   * @param int $priority
-   *   Priority of the breadcrumb builder.
+   * {@inheritdoc}
    */
   public function addBuilder(BreadcrumbBuilderInterface $builder, $priority) {
     $this->builders[$priority][] = $builder;

core/lib/Drupal/Core/Breadcrumb/ChainBreadcrumbBuilderInterface.php

+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\Breadcrumb\ChainBreadcrumbBuilderInterface.
+ */
+
+namespace Drupal\Core\Breadcrumb;
+
+/**
+ * Defines an interface a chained service that builds the breadcrumb.
+ */
+interface ChainBreadcrumbBuilderInterface extends BreadcrumbBuilderInterface {
+
+  /**
+   * Adds another breadcrumb builder.
+   *
+   * @param \Drupal\Core\Breadcrumb\BreadcrumbBuilderInterface $builder
+   *   The breadcrumb builder to add.
+   * @param int $priority
+   *   Priority of the breadcrumb builder.
+   */
+  public function addBuilder(BreadcrumbBuilderInterface $builder, $priority);
+
+}

core/lib/Drupal/Core/DependencyInjection/Compiler/RegisterBreadcrumbBuilderPass.php

@@ -24,9 +24,11 @@ public function process(ContainerBuilder $container) {
       return;
     }
     $manager = $container->getDefinition('breadcrumb');
-    foreach ($container->findTaggedServiceIds('breadcrumb_builder') as $id => $attributes) {
-      $priority = isset($attributes[0]['priority']) ? $attributes[0]['priority'] : 0;
-      $manager->addMethodCall('addBuilder', array(new Reference($id), $priority));
+    if (is_subclass_of($manager->getClass(), 'Drupal\Core\Breadcrumb\ChainBreadcrumbBuilderInterface')) {
+      foreach ($container->findTaggedServiceIds('breadcrumb_builder') as $id => $attributes) {
+        $priority = isset($attributes[0]['priority']) ? $attributes[0]['priority'] : 0;
+        $manager->addMethodCall('addBuilder', array(new Reference($id), $priority));
+      }
     }
   }