Use of tensorflow_decision_forests

Hi,

Firstly, thank you for your great work making the tensorflow library accessible within the java ecosystem.

I would like some guidance or info about how to incorporate a third party library tensorflow_decision_forests (https://www.tensorflow.org/decision_forests) into tensorflow-java. Particularly, I would like to take a trained model and run inference with it from a java app.

I've given this a number of tries on my own. I am using the 0.5.0-SNAPSHOT that targets tf 2.9.1 along with the version of tfdf version 0.2.7 which also targets tf 2.9.1. Without any modifications tensorflow-java or library loading, the error that arises is this:

2022-12-06 08:16:16.811242: I external/org_tensorflow/tensorflow/cc/saved_model/loader.cc:301] SavedModel load for tags { serve }; Status: fail: NOT_FOUND: Op type not registered 'SimpleMLCreateModelResource' in binary running on localhost. Make sure the Op and Kernel are registered in the binary running in this process. Note that if you are loading a saved graph which used ops from tf.contrib, accessing (e.g.) `tf.contrib.resampler` should be done before importing the graph, as contrib ops are lazily registered when the module is first accessed.. Took 16415 microseconds.

This is the obvious error as I'm aware the library introduces custom tensorflow operations which are probably needed to run inference on the saved model. I attempted to raid the shared library .so files from the library distribution and load them using Tensorflow.loadLibrary from within docker containers, but this did not work for me:

TensorFlow.loadLibrary("/usr/local/anaconda3/lib/python3.8/site-packages/tensorflow_decision_forests/tensorflow/ops/inference/inference.so");
TensorFlow.loadLibrary("/usr/local/anaconda3/lib/python3.8/site-packages/tensorflow_decision_forests/tensorflow/ops/training/training.so");

I'm a little out of my depth as to how to get this to work properly, and I would appreciate any helpful info, resources or direction.

I note that the most similar looking issue recently was https://github.com/tensorflow/java/pull/468 -- which also involves loading shared libraries for a 3rd party library.

Start with TensorFlow.loadLibrary and the tensorflow_decision_forests inference.so and training.so paths shown in the issue. Read tensorflow/java#468 for the similar shared-library integration, then determine the supported steps for loading a TFDF SavedModel from Java and document a verified inference path or the missing integration work.