.../Core/Block/MainContentBlockPluginInterface.php |  2 +-
 .../Core/Block/StatefulBlockPluginInterface.php    | 26 ----------------------
 core/modules/block/src/BlockViewBuilder.php        |  5 ++---
 .../src/Plugin/Block/ViewsExposedFilterBlock.php   |  8 +------
 4 files changed, 4 insertions(+), 37 deletions(-)

diff --git a/core/lib/Drupal/Core/Block/MainContentBlockPluginInterface.php b/core/lib/Drupal/Core/Block/MainContentBlockPluginInterface.php
index 605edce..2516348 100644
--- a/core/lib/Drupal/Core/Block/MainContentBlockPluginInterface.php
+++ b/core/lib/Drupal/Core/Block/MainContentBlockPluginInterface.php
@@ -14,7 +14,7 @@
  *
  * @ingroup block_api
  */
-interface MainContentBlockPluginInterface extends StatefulBlockPluginInterface {
+interface MainContentBlockPluginInterface extends BlockPluginInterface {
 
   /**
    * Sets the main content render array.
diff --git a/core/lib/Drupal/Core/Block/StatefulBlockPluginInterface.php b/core/lib/Drupal/Core/Block/StatefulBlockPluginInterface.php
deleted file mode 100644
index 83c28c6..0000000
--- a/core/lib/Drupal/Core/Block/StatefulBlockPluginInterface.php
+++ /dev/null
@@ -1,26 +0,0 @@
-<?php
-
-/**
- * @file
- * Contains \Drupal\Core\Block\StatefulBlockPluginInterface.
- */
-
-namespace Drupal\Core\Block;
-
-/**
- * The interface for blocks that carry state and can hence not be lazily built.
- *
- * Some block plugins are stateful (they carry data in their internal properties
- * and hence are stateful) and can therefore not be lazily rendered.
- *
- * For example: the main content block plugin, which gets the main content
- * injected. If it was lazily rendered, we would not have a way to get the
- * main content block plugin instance that got the main content injected. Thus
- * the state would be lost and it would not be able to render correctly.
- *
- * @see \Drupal\Core\Block\MainContentBlockPluginInterface
- * @see \Drupal\views\Plugin\Block\ViewsExposedFilterBlock
- *
- * @ingroup block_api
- */
-interface StatefulBlockPluginInterface extends BlockPluginInterface { }
diff --git a/core/modules/block/src/BlockViewBuilder.php b/core/modules/block/src/BlockViewBuilder.php
index 990bc0f..6e99faa 100644
--- a/core/modules/block/src/BlockViewBuilder.php
+++ b/core/modules/block/src/BlockViewBuilder.php
@@ -7,9 +7,8 @@
 
 namespace Drupal\block;
 
-use Drupal\block\Entity\Block;
 use Drupal\Component\Utility\SafeMarkup;
-use Drupal\Core\Block\StatefulBlockPluginInterface;
+use Drupal\Core\Block\MainContentBlockPluginInterface;
 use Drupal\Core\Cache\Cache;
 use Drupal\Core\Cache\CacheableMetadata;
 use Drupal\Core\Entity\EntityManagerInterface;
@@ -106,7 +105,7 @@ public function viewMultiple(array $entities = array(), $view_mode = 'full', $la
       // Allow altering of cacheability metadata or setting #create_placeholder.
       $this->moduleHandler->alter(['block_build', "block_build_" . $plugin->getBaseId()], $build[$entity_id], $plugin);
 
-      if ($plugin instanceof StatefulBlockPluginInterface) {
+      if ($plugin instanceof MainContentBlockPluginInterface) {
         // Immediately build a #pre_render-able block, since this block cannot
         // be built lazily.
         $build[$entity_id] += static::buildPreRenderableBlock($entity, $this->moduleHandler());
diff --git a/core/modules/views/src/Plugin/Block/ViewsExposedFilterBlock.php b/core/modules/views/src/Plugin/Block/ViewsExposedFilterBlock.php
index ee46ead..f38d485 100644
--- a/core/modules/views/src/Plugin/Block/ViewsExposedFilterBlock.php
+++ b/core/modules/views/src/Plugin/Block/ViewsExposedFilterBlock.php
@@ -7,8 +7,6 @@
 
 namespace Drupal\views\Plugin\Block;
 
-use Drupal\Core\Block\StatefulBlockPluginInterface;
-
 /**
  * Provides a 'Views Exposed Filter' block.
  *
@@ -17,12 +15,8 @@
  *   admin_label = @Translation("Views Exposed Filter Block"),
  *   deriver = "Drupal\views\Plugin\Derivative\ViewsExposedFilterBlock"
  * )
- *
- * This block uses (and thus depends on) the view that is being shown as the
- * main content. It gets that view injected, so that it has the same view in the
- * exact same state. Hence this block is stateful.
  */
-class ViewsExposedFilterBlock extends ViewsBlockBase implements StatefulBlockPluginInterface {
+class ViewsExposedFilterBlock extends ViewsBlockBase {
 
   /**
    * {@inheritdoc}