fix import for AsyncRetry

Author: parthea

google/api_core/__init__.py

@@ -20,6 +20,3 @@
 from google.api_core import version as api_core_version
 
 __version__ = api_core_version.__version__
-
-# for backwards compatibility, expose async unary retries as google.api_core.retry_async
-from .retry import retry_unary_async as retry_async  # noqa: F401

google/api_core/retry_async/__init__.py

@@ -0,0 +1,34 @@
+# Copyright 2024 Google LLC
+#
+# 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.
+#
+# The following imports are for backwards compatibility with https://github.com/googleapis/python-api-core/blob/4d7d2edee2c108d43deb151e6e0fdceb56b73275/google/api_core/retry_async.py
+#
+# TODO: Revert these imports on the next major version release (https://github.com/googleapis/python-api-core/issues/576)
+from google.api_core import datetime_helpers  # noqa: F401
+from google.api_core import exceptions  # noqa: F401
+from google.api_core.retry import exponential_sleep_generator  # noqa: F401
+from google.api_core.retry import if_exception_type  # noqa: F401
+from google.api_core.retry import if_transient_error  # noqa: F401
+from google.api_core.retry.retry_unary_async import AsyncRetry
+from google.api_core.retry.retry_unary_async import retry_target
+
+__all__ = (
+    "AsyncRetry",
+    "datetime_helpers",
+    "exceptions",
+    "exponential_sleep_generator",
+    "if_exception_type",
+    "if_transient_error",
+    "retry_target",
+)