@JsonProperty
  @Override
  @Nullable
  public Long getMaxTotalRows() {
    return partitionsSpec.getMaxTotalRows();
  }
This class is copied from druid source code
in order to avoid adding additional dependencies on druid-indexing-service.
druid-handler/src/java/org/apache/hadoop/hive/druid/json/SeekableStreamIndexTaskTuningConfig.java