diff -u b/core/modules/block/src/BlockInterface.php b/core/modules/block/src/BlockInterface.php
--- b/core/modules/block/src/BlockInterface.php
+++ b/core/modules/block/src/BlockInterface.php
@@ -126,8 +126,10 @@
    * Returns a list of operation links available for this block.
    *
    * @return array
-   *   An array of operation links. Each operation link is itself an array
-   *   with the following keys:
+   *   An array of operation links. Keys in this array will overwrite keys of
+   *   operations defined in
+   *   \Drupal\block\BlockListBuilder::getDefaultOperations().
+   *   Each operation link is itself an array with the following key
    *     - title: The title the link should display.
    *     - url: The \Drupal\Core\Url object for the link.
    *     - weight: The link weight.
diff -u b/core/modules/block/src/Entity/Block.php b/core/modules/block/src/Entity/Block.php
--- b/core/modules/block/src/Entity/Block.php
+++ b/core/modules/block/src/Entity/Block.php
@@ -2,6 +2,7 @@
 
 namespace Drupal\block\Entity;
 
+use Drupal\Core\Block\BlockOperationsProviderInterface;
 use Drupal\Core\Cache\Cache;
 use Drupal\Core\Condition\ConditionPluginCollection;
 use Drupal\Core\Config\Entity\ConfigEntityBase;
@@ -10,7 +11,6 @@
 use Drupal\Core\Config\Entity\ConfigEntityInterface;
 use Drupal\Core\Entity\EntityWithPluginCollectionInterface;
 use Drupal\Core\Entity\EntityStorageInterface;
-use Drupal\system\BlockOperationsProviderInterface;
 
 /**
  * Defines a Block configuration entity class.
diff -u b/core/modules/block_content/src/Plugin/Block/BlockContentBlock.php b/core/modules/block_content/src/Plugin/Block/BlockContentBlock.php
--- b/core/modules/block_content/src/Plugin/Block/BlockContentBlock.php
+++ b/core/modules/block_content/src/Plugin/Block/BlockContentBlock.php
@@ -6,13 +6,13 @@
 use Drupal\Core\Access\AccessResult;
 use Drupal\Core\Block\BlockBase;
 use Drupal\Core\Block\BlockManagerInterface;
+use Drupal\Core\Block\BlockOperationsProviderInterface;
 use Drupal\Core\Entity\EntityDisplayRepositoryInterface;
 use Drupal\Core\Entity\EntityTypeManagerInterface;
 use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
 use Drupal\Core\Routing\UrlGeneratorInterface;
 use Drupal\Core\Session\AccountInterface;
-use Drupal\system\BlockOperationsProviderInterface;
 use Symfony\Component\DependencyInjection\ContainerInterface;
 
 /**
reverted:
--- b/core/modules/system/src/BlockOperationsProviderInterface.php
+++ /dev/null
@@ -1,22 +0,0 @@
-<?php
-
-namespace Drupal\system;
-
-/**
- * Defines an interface for providing operations links.
- */
-interface BlockOperationsProviderInterface {
-
-  /**
-   * Returns a list of operation links available for this block.
-   *
-   * @return array
-   *   An array of operation links. Each operation link is itself an array
-   *   with the following keys:
-   *     - title: The title the link should display.
-   *     - url: The \Drupal\Core\Url object for the link.
-   *     - weight: The link weight.
-   */
-  public function getOperationLinks();
-
-}
diff -u b/core/modules/system/src/Plugin/Block/SystemMenuBlock.php b/core/modules/system/src/Plugin/Block/SystemMenuBlock.php
--- b/core/modules/system/src/Plugin/Block/SystemMenuBlock.php
+++ b/core/modules/system/src/Plugin/Block/SystemMenuBlock.php
@@ -3,6 +3,7 @@
 namespace Drupal\system\Plugin\Block;
 
 use Drupal\Core\Block\BlockBase;
+use Drupal\Core\Block\BlockOperationsProviderInterface;
 use Drupal\Core\Cache\Cache;
 use Drupal\Core\Extension\ModuleHandlerInterface;
 use Drupal\Core\Form\FormStateInterface;
@@ -12,7 +13,6 @@
 use Drupal\Core\Session\AccountInterface;
 use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
 use Drupal\Core\Url;
-use Drupal\system\BlockOperationsProviderInterface;
 use Drupal\system\Entity\Menu;
 use Symfony\Component\DependencyInjection\ContainerInterface;
 
diff -u b/core/modules/views/src/Plugin/Block/ViewsBlockBase.php b/core/modules/views/src/Plugin/Block/ViewsBlockBase.php
--- b/core/modules/views/src/Plugin/Block/ViewsBlockBase.php
+++ b/core/modules/views/src/Plugin/Block/ViewsBlockBase.php
@@ -2,13 +2,13 @@
 
 namespace Drupal\views\Plugin\Block;
 
+use Drupal\Core\Block\BlockOperationsProviderInterface;
 use Drupal\Core\Url;
 use Drupal\Core\Access\AccessResult;
 use Drupal\Core\Block\BlockBase;
 use Drupal\Core\Extension\ModuleHandlerInterface;
 use Drupal\Core\Form\FormStateInterface;
 use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
-use Drupal\system\BlockOperationsProviderInterface;
 use Drupal\views\ViewExecutableFactory;
 use Drupal\Core\Entity\EntityStorageInterface;
 use Symfony\Component\DependencyInjection\ContainerInterface;
only in patch2:
unchanged:
--- /dev/null
+++ b/core/lib/Drupal/Core/Block/BlockOperationsProviderInterface.php
@@ -0,0 +1,26 @@
+<?php
+
+namespace Drupal\Core\Block;
+
+/**
+ * Defines an interface for providing operations links.
+ *
+ * @see to \Drupal\block\Entity\Block::getOperationLinks()
+ *
+ * @ingroup block_api
+ */
+interface BlockOperationsProviderInterface {
+
+  /**
+   * Returns a list of operation links available for this block.
+   *
+   * @return array
+   *   An array of operation links. Each operation link is itself an array
+   *   with the following keys:
+   *     - title: The title the link should display.
+   *     - url: The \Drupal\Core\Url object for the link.
+   *     - weight: The link weight.
+   */
+  public function getOperationLinks();
+
+}