code: public static String updatePartitionLocation(String outputDataPartitionLocation, WorkUnitState workUnitState,
        Optional<Path> destPartitionLocation)
        throws DataConversionException {
  
      if (workUnitState.getPropAsBoolean(HIVE_DATASET_PARTITION_OVERWRITE, DEFAULT_HIVE_DATASET_PARTITION_OVERWRITE)) {
        return outputDataPartitionLocation;
      }
      if (!destPartitionLocation.isPresent()) {
        return outputDataPartitionLocation;
      }
      long timeStamp = System.currentTimeMillis();
      return StringUtils.join(Arrays.asList(outputDataPartitionLocation, timeStamp), '/');
    }
docs: If partition already exists then new partition location will be a separate time stamp dir
  If partition location is /a/b/c/<oldTimeStamp> then new partition location is /a/b/c/<currentTimeStamp>
  If partition location is /a/b/c/ then new partition location is /a/b/c/<currentTimeStamp>