diff --git a/core/modules/migrate/src/Plugin/migrate/source/SourcePluginBase.php b/core/modules/migrate/src/Plugin/migrate/source/SourcePluginBase.php
index e355850..9362b9c 100644
--- a/core/modules/migrate/src/Plugin/migrate/source/SourcePluginBase.php
+++ b/core/modules/migrate/src/Plugin/migrate/source/SourcePluginBase.php
@@ -15,6 +15,12 @@
 /**
  * The base class for all source plugins.
  *
+ * Available configuration keys:
+ * - cache_counts: Whether this instance should cache the source count.
+ * - skip_count: Whether this instance should not attempt to count the source.
+ * - track_changes: Flags whether to track changes to incoming data.
+ * - high_water_property: Information on the property used as the high-water mark.
+ *
  * @see \Drupal\migrate\Plugin\MigratePluginManager
  * @see \Drupal\migrate\Annotation\MigrateSource
  * @see \Drupal\migrate\Plugin\MigrateSourceInterface