@Override
    public SystemStreamPartition deserialize(JsonParser jsonParser, DeserializationContext context) throws IOException, JsonProcessingException {
      ObjectCodec oc = jsonParser.getCodec();
      JsonNode node = oc.readTree(jsonParser);
      String system = node.get("system").textValue();
      String stream = node.get("stream").textValue();
      Partition partition = new Partition(node.get("partition").intValue());
      return new SystemStreamPartition(system, stream, partition);
    }
Builds {@link ObjectNode} which matches the {@link JobModel} built in setup.
samza-core/src/test/java/org/apache/samza/serializers/model/TestSamzaObjectMapper.java