core/modules/big_pipe/src/Controller/BigPipeController.php              | 2 ++
 .../big_pipe/src/EventSubscriber/HtmlResponseBigPipeSubscriber.php      | 2 ++
 .../big_pipe/src/EventSubscriber/NoBigPipeRouteAlterSubscriber.php      | 2 ++
 core/modules/big_pipe/src/Render/BigPipe.php                            | 2 ++
 core/modules/big_pipe/src/Render/BigPipeInterface.php                   | 2 ++
 core/modules/big_pipe/src/Render/BigPipeResponse.php                    | 2 ++
 .../modules/big_pipe/src/Render/BigPipeResponseAttachmentsProcessor.php | 2 ++
 core/modules/big_pipe/src/Render/Placeholder/BigPipeStrategy.php        | 2 ++
 8 files changed, 16 insertions(+)

diff --git a/core/modules/big_pipe/src/Controller/BigPipeController.php b/core/modules/big_pipe/src/Controller/BigPipeController.php
index b9f02d0..7d8156c 100644
--- a/core/modules/big_pipe/src/Controller/BigPipeController.php
+++ b/core/modules/big_pipe/src/Controller/BigPipeController.php
@@ -12,6 +12,8 @@
 
 /**
  * Returns responses for BigPipe module routes.
+ *
+ * @internal
  */
 class BigPipeController {
 
diff --git a/core/modules/big_pipe/src/EventSubscriber/HtmlResponseBigPipeSubscriber.php b/core/modules/big_pipe/src/EventSubscriber/HtmlResponseBigPipeSubscriber.php
index f8cef10..355d766 100644
--- a/core/modules/big_pipe/src/EventSubscriber/HtmlResponseBigPipeSubscriber.php
+++ b/core/modules/big_pipe/src/EventSubscriber/HtmlResponseBigPipeSubscriber.php
@@ -14,6 +14,8 @@
  *
  * @see \Drupal\big_pipe\Render\BigPipeInterface
  *
+ * @internal
+ *
  * @todo Refactor once https://www.drupal.org/node/2577631 lands.
  */
 class HtmlResponseBigPipeSubscriber implements EventSubscriberInterface {
diff --git a/core/modules/big_pipe/src/EventSubscriber/NoBigPipeRouteAlterSubscriber.php b/core/modules/big_pipe/src/EventSubscriber/NoBigPipeRouteAlterSubscriber.php
index 516aeb4..a08ab22 100644
--- a/core/modules/big_pipe/src/EventSubscriber/NoBigPipeRouteAlterSubscriber.php
+++ b/core/modules/big_pipe/src/EventSubscriber/NoBigPipeRouteAlterSubscriber.php
@@ -8,6 +8,8 @@
 
 /**
  * Sets the '_no_big_pipe' option on select routes.
+ *
+ * @internal
  */
 class NoBigPipeRouteAlterSubscriber implements EventSubscriberInterface {
 
diff --git a/core/modules/big_pipe/src/Render/BigPipe.php b/core/modules/big_pipe/src/Render/BigPipe.php
index 348e759..c96e305 100644
--- a/core/modules/big_pipe/src/Render/BigPipe.php
+++ b/core/modules/big_pipe/src/Render/BigPipe.php
@@ -22,6 +22,8 @@
 
 /**
  * The default BigPipe service.
+ *
+ * @internal
  */
 class BigPipe implements BigPipeInterface {
 
diff --git a/core/modules/big_pipe/src/Render/BigPipeInterface.php b/core/modules/big_pipe/src/Render/BigPipeInterface.php
index 988a512..3b2aa4c 100644
--- a/core/modules/big_pipe/src/Render/BigPipeInterface.php
+++ b/core/modules/big_pipe/src/Render/BigPipeInterface.php
@@ -128,6 +128,8 @@
  *
  * @see \Drupal\big_pipe\EventSubscriber\HtmlResponseBigPipeSubscriber
  * @see \Drupal\big_pipe\Render\Placeholder\BigPipeStrategy
+ *
+ * @internal
  */
 interface BigPipeInterface {
 
diff --git a/core/modules/big_pipe/src/Render/BigPipeResponse.php b/core/modules/big_pipe/src/Render/BigPipeResponse.php
index ba4d5f0..8b0c14c 100644
--- a/core/modules/big_pipe/src/Render/BigPipeResponse.php
+++ b/core/modules/big_pipe/src/Render/BigPipeResponse.php
@@ -13,6 +13,8 @@
  *
  * @see \Drupal\big_pipe\Render\BigPipeInterface
  *
+ * @internal
+ *
  * @todo Will become obsolete with https://www.drupal.org/node/2577631
  */
 class BigPipeResponse extends HtmlResponse {
diff --git a/core/modules/big_pipe/src/Render/BigPipeResponseAttachmentsProcessor.php b/core/modules/big_pipe/src/Render/BigPipeResponseAttachmentsProcessor.php
index 32640c2..7c833de 100644
--- a/core/modules/big_pipe/src/Render/BigPipeResponseAttachmentsProcessor.php
+++ b/core/modules/big_pipe/src/Render/BigPipeResponseAttachmentsProcessor.php
@@ -18,6 +18,8 @@
  *
  * @see \Drupal\Core\Render\HtmlResponseAttachmentsProcessor
  * @see \Drupal\big_pipe\Render\BigPipeInterface
+ *
+ * @internal
  */
 class BigPipeResponseAttachmentsProcessor extends HtmlResponseAttachmentsProcessor {
 
diff --git a/core/modules/big_pipe/src/Render/Placeholder/BigPipeStrategy.php b/core/modules/big_pipe/src/Render/Placeholder/BigPipeStrategy.php
index dab9f8c..e35d222 100644
--- a/core/modules/big_pipe/src/Render/Placeholder/BigPipeStrategy.php
+++ b/core/modules/big_pipe/src/Render/Placeholder/BigPipeStrategy.php
@@ -56,6 +56,8 @@
  * different placeholders are actually replaced.
  *
  * @see \Drupal\big_pipe\Render\BigPipeInterface
+ *
+ * @internal
  */
 class BigPipeStrategy implements PlaceholderStrategyInterface {