code: private void rollback(final short vbucket, final long toSeqno) {
      final Queue<BufferedEvent> queue = partitionQueues.get(vbucket);
  
      synchronized (queue) {
        for (Iterator<BufferedEvent> i = queue.iterator(); i.hasNext(); ) {
          final BufferedEvent event = i.next();
          final boolean eventSeqnoIsGreaterThanRollbackSeqno = Long.compareUnsigned(event.seqno, toSeqno) > 0;
          if (eventSeqnoIsGreaterThanRollbackSeqno) {
            LOGGER.trace("Dropping event with seqno {} from stream buffer for partition {}", event.seqno, vbucket);
            event.discard();
            i.remove();
          }
        }
      }
    }
docs: Discard any buffered events in the given vBucket with sequence numbers
  higher than the given sequence number.