code: public SnsMessage unmarshall(JsonNode rawMessage) {
          SnsJsonNode message = new SnsJsonNode(rawMessage);
          return unmarshallBase(createSubMessage(message), message).build();
      }
docs: Unmarshalls the given {@link JsonNode} into the appropriate sub type based on the {@link #TYPE}.
  
  @param rawMessage JSON message.
  @return Unmarshalled message.