private boolean startNonceOperation() throws IOException {
      if (
        region.rsServices == null || region.rsServices.getNonceManager() == null
          || nonce == HConstants.NO_NONCE
      ) {
        return true;
      }
      boolean canProceed;
      try {
        canProceed =
          region.rsServices.getNonceManager().startOperation(nonceGroup, nonce, region.rsServices);
      } catch (InterruptedException ex) {
        throw new InterruptedIOException("Nonce start operation interrupted");
      }
      return canProceed;
    }
Starts the nonce operation for a mutation, if needed.
@return whether to proceed this mutation.
hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegion.java