private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
    in.defaultReadObject();
    this.mapper = new ObjectMapper();
  }
Constructs a JsonSerdeV2 that (de)serializes POJOs of class {@code clazz}.

@param clazz the class of the POJO being (de)serialized.
samza-api/src/main/java/org/apache/samza/serializers/JsonSerdeV2.java