diff --git a/core/modules/aggregator/src/Annotation/AggregatorFetcher.php b/core/modules/aggregator/src/Annotation/AggregatorFetcher.php
index 0fbee2f..5a3f226 100644
--- a/core/modules/aggregator/src/Annotation/AggregatorFetcher.php
+++ b/core/modules/aggregator/src/Annotation/AggregatorFetcher.php
@@ -12,6 +12,14 @@
 /**
  * Defines a Plugin annotation object for aggregator fetcher plugins.
  *
+ * Plugin Namespace: Plugin\aggregator\fetcher
+ * For a working example, see \Drupal\aggregator\Plugin\aggregator\fetcher\DefaultFetcher
+ *
+ * @see \Drupal\aggregator\Plugin\AggregatorPluginManager
+ * @see \Drupal\aggregator\Plugin\FetcherInterface
+ * @see \Drupal\aggregator\Plugin\AggregatorPluginSettingsBase
+ * @see plugin_api
+ *
  * @Annotation
  */
 class AggregatorFetcher extends Plugin {
diff --git a/core/modules/aggregator/src/Annotation/AggregatorParser.php b/core/modules/aggregator/src/Annotation/AggregatorParser.php
index c36a5e8..4373b06 100644
--- a/core/modules/aggregator/src/Annotation/AggregatorParser.php
+++ b/core/modules/aggregator/src/Annotation/AggregatorParser.php
@@ -12,6 +12,14 @@
 /**
  * Defines a Plugin annotation object for aggregator parser plugins.
  *
+ * Plugin Namespace: Plugin\aggregator\parser
+ * For a working example, see \Drupal\aggregator\Plugin\aggregator\parser\DefaultParser
+ *
+ * @see \Drupal\aggregator\Plugin\AggregatorPluginManager
+ * @see \Drupal\aggregator\Plugin\FetcherInterface
+ * @see \Drupal\aggregator\Plugin\AggregatorPluginSettingsBase
+ * @see plugin_api
+ *
  * @Annotation
  */
 class AggregatorParser extends Plugin {
diff --git a/core/modules/aggregator/src/Annotation/AggregatorProcessor.php b/core/modules/aggregator/src/Annotation/AggregatorProcessor.php
index 7ab4827..18269c1 100644
--- a/core/modules/aggregator/src/Annotation/AggregatorProcessor.php
+++ b/core/modules/aggregator/src/Annotation/AggregatorProcessor.php
@@ -12,6 +12,14 @@
 /**
  * Defines a Plugin annotation object for aggregator processor plugins.
  *
+ * Plugin Namespace: Plugin\aggregator\processor
+ * For a working example, see \Drupal\aggregator\Plugin\aggregator\processor\DefaultProcessor
+ *
+ * @see \Drupal\aggregator\Plugin\AggregatorPluginManager
+ * @see \Drupal\aggregator\Plugin\FetcherInterface
+ * @see \Drupal\aggregator\Plugin\AggregatorPluginSettingsBase
+ * @see plugin_api
+ *
  * @Annotation
  */
 class AggregatorProcessor extends Plugin {
diff --git a/core/modules/aggregator/src/Plugin/AggregatorPluginManager.php b/core/modules/aggregator/src/Plugin/AggregatorPluginManager.php
index 84196cd..5be6feb 100644
--- a/core/modules/aggregator/src/Plugin/AggregatorPluginManager.php
+++ b/core/modules/aggregator/src/Plugin/AggregatorPluginManager.php
@@ -12,7 +12,14 @@
 use Drupal\Core\Plugin\DefaultPluginManager;
 
 /**
- * Manages aggregator plugins.
+ * Provides aggregator plugins.
+ *
+ * @see \Drupal\aggregator\Annotation\AggregatorParser
+ * @see \Drupal\aggregator\Annotation\AggregatorFetcher
+ * @see \Drupal\aggregator\Annotation\AggregatorProcessor
+ * @see \Drupal\aggregator\Plugin\AggregatorPluginSettingsBase
+ * @see \Drupal\aggregator\Plugin\FetcherInterface
+ * @see plugin_api
  */
 class AggregatorPluginManager extends DefaultPluginManager {
 
diff --git a/core/modules/aggregator/src/Plugin/AggregatorPluginSettingsBase.php b/core/modules/aggregator/src/Plugin/AggregatorPluginSettingsBase.php
index 80493c0..0133d33 100644
--- a/core/modules/aggregator/src/Plugin/AggregatorPluginSettingsBase.php
+++ b/core/modules/aggregator/src/Plugin/AggregatorPluginSettingsBase.php
@@ -13,6 +13,13 @@
 
 /**
  * Base class for aggregator plugins that implement settings forms.
+ *
+ * @see \Drupal\aggregator\Annotation\AggregatorParser
+ * @see \Drupal\aggregator\Annotation\AggregatorFetcher
+ * @see \Drupal\aggregator\Annotation\AggregatorProcessor
+ * @see \Drupal\aggregator\Plugin\AggregatorPluginManager
+ * @see \Drupal\aggregator\Plugin\FetcherInterface
+ * @see plugin_api
  */
 abstract class AggregatorPluginSettingsBase extends PluginBase implements PluginFormInterface, ConfigurablePluginInterface {