Add __init__.py to the contrib/cluster_resolver directory so that the Cluster Resolver classes within this are visible to open source TensorFlow users.

PiperOrigin-RevId: 163733781

tensorflow/contrib/cluster_resolver/BUILD

@@ -23,7 +23,10 @@ filegroup(
 
 py_library(
     name = "cluster_resolver_pip",
-    srcs = ["python/training/__init__.py"],
+    srcs = [
+        "__init__.py",
+        "python/training/__init__.py",
+    ],
     srcs_version = "PY2AND3",
     deps = [
         ":cluster_resolver_py",

tensorflow/contrib/cluster_resolver/__init__.py

@@ -0,0 +1,28 @@
+# Copyright 2017 The TensorFlow Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+# =============================================================================
+
+"""Standard imports for Cluster Resolvers."""
+
+from __future__ import absolute_import
+from __future__ import division
+from __future__ import print_function
+
+# pylint: disable=wildcard-import,unused-import
+from tensorflow.contrib.cluster_resolver.python.training.cluster_resolver import ClusterResolver
+from tensorflow.contrib.cluster_resolver.python.training.cluster_resolver import SimpleClusterResolver
+from tensorflow.contrib.cluster_resolver.python.training.cluster_resolver import UnionClusterResolver
+from tensorflow.contrib.cluster_resolver.python.training.gce_cluster_resolver import GceClusterResolver
+from tensorflow.contrib.cluster_resolver.python.training.tpu_cluster_resolver import TPUClusterResolver
+# pylint: enable=wildcard-import,unused-import