public void addTimeout(HashedWheelTimeout timeout) {
            assert timeout.bucket == null;
            timeout.bucket = this;
            if (head == null) {
                head = tail = timeout;
            } else {
                tail.next = timeout;
                timeout.prev = tail;
                tail = timeout;
            }
        }
Add {@link HashedWheelTimeout} to this bucket.
jraft-core/src/main/java/com/alipay/sofa/jraft/util/timer/HashedWheelTimer.java