/guava/guava/src/com/google/common/util/concurrent/AbstractFuture.java
head = onto;
head = head.next;
@CheckForNull private Listener clearListeners(@CheckForNull Listener onto) { Listener head = ATOMIC_HELPER.gasListeners(this, Listener.TOMBSTONE); Listener reversedList = onto; while (head != null) { Listener tmp = head; <extra_id_0> tmp.next = reversedList; reversedList = tmp; } return reversedList; } @Override