Remove the code that handles serializing raw tf.Tensor values to th…

…e `Value` protobuf.

This change brings TFF closer to isolating the TF dependencies in the `tensorflow` package.

PiperOrigin-RevId: 649311211

RELEASE.md

@@ -8,6 +8,10 @@ and this project adheres to
 
 ## Unreleased
 
+### Removed
+
+*   Serializing raw `tf.Tensor` values to the `Value` protobuf.
+
 ## Release 0.82.0
 
 ### Added

tensorflow_federated/python/core/impl/executors/value_serialization.py

@@ -100,15 +100,6 @@ def _serialize_tensor_value(
     ValueError: If the value is malformed.
   """
   original_value = value
-  if tf.is_tensor(value):
-    if isinstance(value, tf.Variable):
-      value = value.read_value()
-    if isinstance(value, tf.Tensor) and not tf.is_symbolic_tensor(value):
-      value = value.numpy()
-    else:
-      # Attempt to extract the value using the current graph context.
-      with tf.compat.v1.Session() as sess:
-        value = sess.run(value)
   # If we got a string or bytes scalar, wrap it in numpy so it has a dtype and
   # shape.
   if isinstance(value, (np.bytes_, np.str_, bytes, str)):

tensorflow_federated/python/core/impl/executors/value_serialization_test.py

@@ -71,26 +71,6 @@ def test_serialize_deserialize_tensor_value_unk_shape_without_hint(self):
     self.assertEqual(y.dtype, serialize_type_spec.dtype)
     self.assertAllEqual(x, y)
 
-  @parameterized.named_parameters(TENSOR_SERIALIZATION_TEST_PARAMS)
-  def test_serialize_deserialize_tensor_value_without_hint_graph_mode(
-      self, x, serialize_type_spec
-  ):
-    # Test serializing non-eager tensors.
-    with tf.Graph().as_default():
-      tensor_x = tf.convert_to_tensor(x)
-      value_proto, value_type = value_serialization.serialize_value(
-          tensor_x, serialize_type_spec
-      )
-    type_test_utils.assert_types_identical(value_type, serialize_type_spec)
-    y, deserialize_type_spec = value_serialization.deserialize_value(
-        value_proto
-    )
-    type_test_utils.assert_types_identical(
-        deserialize_type_spec, serialize_type_spec
-    )
-    self.assertEqual(y.dtype, serialize_type_spec.dtype)
-    self.assertAllEqual(x, y)
-
   @parameterized.named_parameters(TENSOR_SERIALIZATION_TEST_PARAMS)
   def test_serialize_deserialize_tensor_value_with_hint(
       self, x, serialize_type_spec