+ /**
+ * Adds an entity to a subqueue
+ *
+ * @param \Drupal\Core\Entity\EntityInterface $entity
+ * An entity object.
+ *
+ * @return $this
+ */
+ public function addItem(EntityInterface $entity);
+
+ /**
+ * Removes an entity from a subqueue
+ *
+ * @param \Drupal\Core\Entity\EntityInterface $entity
+ * An entity object.
+ *
+ * @return $this
+ */
+ public function removeItem(EntityInterface $entity);
+