Replaced SubClass with subclassed.

Change-Id: Ibf43764cbf4024890b68a2550ae44c6e52aade31

Author: wwwind

tensorflow_model_optimization/python/core/clustering/keras/cluster.py

@@ -133,7 +133,7 @@ def _add_clustering_wrapper(layer):
       # There is no available public API to do this check.
       if (not layer._is_graph_network and
           not isinstance(layer, keras.models.Sequential)):
-        raise ValueError("SubClass models are not supported currently.")
+        raise ValueError("Subclassed models are not supported currently.")
 
       return keras.models.clone_model(layer,
                                     input_tensors=None,

tensorflow_model_optimization/python/core/clustering/keras/cluster_test.py

@@ -403,7 +403,7 @@ def testClusterSubclassModelAsSubmodel(self):
         layers.Dense(10),
         model_subclass
     ])
-    with self.assertRaisesRegexp(ValueError, "SubClass models.*"):
+    with self.assertRaisesRegexp(ValueError, "Subclassed models.*"):
       _ = cluster.cluster_weights(model, **self.params)
 
   @keras_parameterized.run_all_keras_modes