docs: public void stable(long seqno) {
          lock.lock();
          try {
              if(seqno <= low)
                  return;
              if(seqno > hd)
                  throw new IllegalArgumentException("seqno " + seqno + " cannot be bigger than hd (" + hd + ")");
  
              int from=index(low+1), length=(int)(seqno - low), capacity=capacity();
              for(int i=from; i < from+length; i++) {
                  int index=i & (capacity - 1);
                  buf[index]=null;
              }
  
              // Releases some of the blocked adders
              if(seqno > low) {
                  low=seqno;
                  buffer_full.signalAll();
              }
          }
          finally {
              lock.unlock();
          }
      }