@Override public ParseSpec withTimestampSpec(TimestampSpec spec) {
    return new AvroParseSpec(spec, getDimensionsSpec(), flattenSpec);
  }
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/AvroParseSpec.java