code: public static PutAction mergePutActions(byte[] keyBytes,
        List<PutAction> putActionList) {
      VersionCheckAction checkAction = null;
      List<Put> putsToMerge = new ArrayList<Put>();
      for (PutAction putActionToMerge : putActionList) {
        putsToMerge.add(putActionToMerge.getPut());
        VersionCheckAction checkActionToMerge = putActionToMerge.getVersionCheckAction();
        if (checkActionToMerge != null) {
          checkAction = checkActionToMerge;
        }
      }
      Put put = mergePuts(keyBytes, putsToMerge);
      return new PutAction(put, checkAction);
    }
docs: Given a list of PutActions, create a new PutAction with the values in each
  put merged together. It is expected that no puts have a value for the same
  fully qualified column. Return the new PutAction.
  
  @param key
  The key of the new put.
  @param putActionList
  The list of PutActions to merge
  @return the new PutAction instance