Issue #2549017 by pjonckiere: Add getGroup() and getGroupLabel() to an interface and add docs

core/lib/Drupal/Core/Entity/EntityTypeInterface.php

@@ -651,6 +651,20 @@ public function getUriCallback();
    */
   public function setUriCallback($callback);
 
+  /**
+   * Gets the machine name of the entity type group.
+   *
+   * @return string
+   */
+  public function getGroup();
+
+  /**
+   * Gets the human-readable name of the entity type group.
+   *
+   * @return string
+   */
+  public function getGroupLabel();
+
   /**
    * The list cache contexts associated with this entity type.
    *