@Override
    public void serialize(SystemStreamPartition systemStreamPartition, JsonGenerator jsonGenerator, SerializerProvider provider) throws IOException, JsonProcessingException {
      Map<String, Object> systemStreamPartitionMap = new HashMap<String, Object>();
      systemStreamPartitionMap.put("system", systemStreamPartition.getSystem());
      systemStreamPartitionMap.put("stream", systemStreamPartition.getStream());
      systemStreamPartitionMap.put("partition", systemStreamPartition.getPartition());
      systemStreamPartitionMap.put("keyBucket", systemStreamPartition.getKeyBucket());
      jsonGenerator.writeObject(systemStreamPartitionMap);
    }
@return Returns a new ObjectMapper that's been configured to (de)serialize
        Samza's job data model, and simple data types such as TaskName,
        Partition, Config, and SystemStreamPartition.
samza-core/src/main/java/org/apache/samza/serializers/model/SamzaObjectMapper.java