diff --git a/content_entity_example/src/ContactInterface.php b/content_entity_example/src/ContactInterface.php
index c9501cb..0476336 100755
--- a/content_entity_example/src/ContactInterface.php
+++ b/content_entity_example/src/ContactInterface.php
@@ -8,11 +8,19 @@ namespace Drupal\content_entity_example;
 
 use Drupal\Core\Entity\ContentEntityInterface;
 use Drupal\user\EntityOwnerInterface;
+use Drupal\Core\Entity\EntityChangedInterface;
 
 /**
  * Provides an interface defining a Contact entity.
  * @ingroup content_entity_example
  */
-interface ContactInterface extends ContentEntityInterface, EntityOwnerInterface {
-
+interface ContactInterface extends ContentEntityInterface, EntityOwnerInterface, EntityChangedInterface {
+  /**
+   * Returns the entity creation timestamp.
+   *
+   * @return int
+   *   Creation timestamp of the entity.
+   */
+  public function getCreatedTime();
 }
+