code: @JsonProperty
    @Deprecated
    public SeekableStreamEndSequenceNumbers<String, String> getStartPartitions()
    {
      final SeekableStreamStartSequenceNumbers<String, String> startSequenceNumbers = getStartSequenceNumbers();
      return new SeekableStreamEndSequenceNumbers<>(
          startSequenceNumbers.getStream(),
          startSequenceNumbers.getPartitionSequenceNumberMap()
      );
    }
docs: This method is for compatibilty so that newer version of KinesisIndexTaskIOConfig can be read by
  old version of Druid. Note that this method returns end sequence numbers instead of start. This is because
  {@link SeekableStreamStartSequenceNumbers} didn't exist before.
  
  A SeekableStreamEndSequenceNumbers (has no exclusivity info) is returned here because the Kinesis extension
  previously stored exclusivity info separately in exclusiveStartSequenceNumberPartitions.