should switch to
        `tf.estimator.Estimator.experimental_export_all_saved_models`.
    *   Update `regression_head` to the new Head API for Canned Estimator V2.
    *   Switch `multi_class_head` to Head API for Canned Estimator V2.
    *   Replace all occurrences of `tf.contrib.estimator.InMemoryEvaluatorHook`
        and `tf.contrib.estimator.make_stop_at_checkpoint_step_hook` with

tfrt/mlrt/kernel,tensorflow/core/tfrt/mlrt/bytecode,tensorflow/core/tfrt/mlrt/interpreter,tensorflow/compiler/mlir/tfrt/translate/mlrt,tensorflow/compiler/mlir/tfrt/translate/mlrt/testdata,tensorflow/core/tfrt/gpu,tensorflow/core/tfrt/run_handler_thread_pool,tensorflow/core/tfrt/runtime,tensorflow/core/tfrt/saved_model,tensorflow/core/tfrt/graph_executor,tensorflow/core/tfrt/saved_model/tests,tensorflow/core/tfrt/tpu,tensorflow/core/tfrt/utils,tensorflow/core/tfrt/utils/debug,tensorflow/core/tfr...