code: public final void sendSentinel(long txnId, int partitionId) {
          final long initiatorHSId = m_cartographer.getHSIdForSinglePartitionMaster(partitionId);
          sendSentinel(txnId, initiatorHSId, -1, -1, true);
      }
docs: Send a command log replay sentinel to the given partition.
  @param txnId
  @param partitionId