diff --git a/.github/.OwlBot.lock.yaml b/.github/.OwlBot.lock.yaml
index 7d98291..cb89b2e 100644
--- a/.github/.OwlBot.lock.yaml
+++ b/.github/.OwlBot.lock.yaml
@@ -1,3 +1,3 @@
 docker:
   image: gcr.io/cloud-devrel-public-resources/owlbot-python:latest
-  digest: sha256:58f73ba196b5414782605236dd0712a73541b44ff2ff4d3a36ec41092dd6fa5b
+  digest: sha256:ec49167c606648a063d1222220b48119c912562849a0528f35bfb592a9f72737
diff --git a/.kokoro/docs/common.cfg b/.kokoro/docs/common.cfg
index eef1593..873defd 100644
--- a/.kokoro/docs/common.cfg
+++ b/.kokoro/docs/common.cfg
@@ -30,6 +30,7 @@ env_vars: {
 
 env_vars: {
     key: "V2_STAGING_BUCKET"
+    # Push google cloud library docs to the Cloud RAD bucket `docs-staging-v2`
     value: "docs-staging-v2"
 }
 
diff --git a/CHANGELOG.md b/CHANGELOG.md
index c2edf97..9ede526 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,18 @@
 # Changelog
 
+### [0.3.1](https://www.github.com/googleapis/python-network-security/compare/v0.3.0...v0.3.1) (2021-11-02)
+
+
+### Bug Fixes
+
+* **deps:** drop packaging dependency ([518f32b](https://www.github.com/googleapis/python-network-security/commit/518f32b90db80cd8a5b2774aba8c9a4b13ea1f57))
+* **deps:** require google-api-core >= 1.28.0 ([518f32b](https://www.github.com/googleapis/python-network-security/commit/518f32b90db80cd8a5b2774aba8c9a4b13ea1f57))
+
+
+### Documentation
+
+* list oneofs in docstring ([518f32b](https://www.github.com/googleapis/python-network-security/commit/518f32b90db80cd8a5b2774aba8c9a4b13ea1f57))
+
 ## [0.3.0](https://www.github.com/googleapis/python-network-security/compare/v0.2.0...v0.3.0) (2021-10-14)
 
 
diff --git a/docs/index.rst b/docs/index.rst
index 7b1e13f..85a095f 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -2,6 +2,7 @@
 
 .. include:: multiprocessing.rst
 
+
 API Reference
 -------------
 .. toctree::
@@ -10,12 +11,13 @@ API Reference
     network_security_v1beta1/services
     network_security_v1beta1/types
 
+
 Changelog
 ---------
 
 For a list of all ``google-cloud-network-security`` releases:
 
 .. toctree::
-   :maxdepth: 2
+    :maxdepth: 2
 
-   changelog
\ No newline at end of file
+    changelog
diff --git a/google/cloud/network_security_v1beta1/services/network_security/async_client.py b/google/cloud/network_security_v1beta1/services/network_security/async_client.py
index ab1700e..e949a61 100644
--- a/google/cloud/network_security_v1beta1/services/network_security/async_client.py
+++ b/google/cloud/network_security_v1beta1/services/network_security/async_client.py
@@ -19,13 +19,15 @@
 from typing import Dict, Sequence, Tuple, Type, Union
 import pkg_resources
 
-import google.api_core.client_options as ClientOptions  # type: ignore
+from google.api_core.client_options import ClientOptions  # type: ignore
 from google.api_core import exceptions as core_exceptions  # type: ignore
 from google.api_core import gapic_v1  # type: ignore
 from google.api_core import retry as retries  # type: ignore
 from google.auth import credentials as ga_credentials  # type: ignore
 from google.oauth2 import service_account  # type: ignore
 
+OptionalRetry = Union[retries.Retry, object]
+
 from google.api_core import operation  # type: ignore
 from google.api_core import operation_async  # type: ignore
 from google.cloud.network_security_v1beta1.services.network_security import pagers
@@ -193,10 +195,12 @@ def __init__(
 
     async def list_authorization_policies(
         self,
-        request: authorization_policy.ListAuthorizationPoliciesRequest = None,
+        request: Union[
+            authorization_policy.ListAuthorizationPoliciesRequest, dict
+        ] = None,
         *,
         parent: str = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> pagers.ListAuthorizationPoliciesAsyncPager:
@@ -204,7 +208,7 @@ async def list_authorization_policies(
         location.
 
         Args:
-            request (:class:`google.cloud.network_security_v1beta1.types.ListAuthorizationPoliciesRequest`):
+            request (Union[google.cloud.network_security_v1beta1.types.ListAuthorizationPoliciesRequest, dict]):
                 The request object. Request used with the
                 ListAuthorizationPolicies method.
             parent (:class:`str`):
@@ -275,17 +279,17 @@ async def list_authorization_policies(
 
     async def get_authorization_policy(
         self,
-        request: authorization_policy.GetAuthorizationPolicyRequest = None,
+        request: Union[authorization_policy.GetAuthorizationPolicyRequest, dict] = None,
         *,
         name: str = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> authorization_policy.AuthorizationPolicy:
         r"""Gets details of a single AuthorizationPolicy.
 
         Args:
-            request (:class:`google.cloud.network_security_v1beta1.types.GetAuthorizationPolicyRequest`):
+            request (Union[google.cloud.network_security_v1beta1.types.GetAuthorizationPolicyRequest, dict]):
                 The request object. Request used by the
                 GetAuthorizationPolicy method.
             name (:class:`str`):
@@ -352,12 +356,14 @@ async def get_authorization_policy(
 
     async def create_authorization_policy(
         self,
-        request: gcn_authorization_policy.CreateAuthorizationPolicyRequest = None,
+        request: Union[
+            gcn_authorization_policy.CreateAuthorizationPolicyRequest, dict
+        ] = None,
         *,
         parent: str = None,
         authorization_policy: gcn_authorization_policy.AuthorizationPolicy = None,
         authorization_policy_id: str = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation_async.AsyncOperation:
@@ -365,7 +371,7 @@ async def create_authorization_policy(
         and location.
 
         Args:
-            request (:class:`google.cloud.network_security_v1beta1.types.CreateAuthorizationPolicyRequest`):
+            request (Union[google.cloud.network_security_v1beta1.types.CreateAuthorizationPolicyRequest, dict]):
                 The request object. Request used by the
                 CreateAuthorizationPolicy method.
             parent (:class:`str`):
@@ -463,11 +469,13 @@ async def create_authorization_policy(
 
     async def update_authorization_policy(
         self,
-        request: gcn_authorization_policy.UpdateAuthorizationPolicyRequest = None,
+        request: Union[
+            gcn_authorization_policy.UpdateAuthorizationPolicyRequest, dict
+        ] = None,
         *,
         authorization_policy: gcn_authorization_policy.AuthorizationPolicy = None,
         update_mask: field_mask_pb2.FieldMask = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation_async.AsyncOperation:
@@ -475,7 +483,7 @@ async def update_authorization_policy(
         AuthorizationPolicy.
 
         Args:
-            request (:class:`google.cloud.network_security_v1beta1.types.UpdateAuthorizationPolicyRequest`):
+            request (Union[google.cloud.network_security_v1beta1.types.UpdateAuthorizationPolicyRequest, dict]):
                 The request object. Request used by the
                 UpdateAuthorizationPolicy method.
             authorization_policy (:class:`google.cloud.network_security_v1beta1.types.AuthorizationPolicy`):
@@ -565,17 +573,19 @@ async def update_authorization_policy(
 
     async def delete_authorization_policy(
         self,
-        request: authorization_policy.DeleteAuthorizationPolicyRequest = None,
+        request: Union[
+            authorization_policy.DeleteAuthorizationPolicyRequest, dict
+        ] = None,
         *,
         name: str = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation_async.AsyncOperation:
         r"""Deletes a single AuthorizationPolicy.
 
         Args:
-            request (:class:`google.cloud.network_security_v1beta1.types.DeleteAuthorizationPolicyRequest`):
+            request (Union[google.cloud.network_security_v1beta1.types.DeleteAuthorizationPolicyRequest, dict]):
                 The request object. Request used by the
                 DeleteAuthorizationPolicy method.
             name (:class:`str`):
@@ -658,10 +668,10 @@ async def delete_authorization_policy(
 
     async def list_server_tls_policies(
         self,
-        request: server_tls_policy.ListServerTlsPoliciesRequest = None,
+        request: Union[server_tls_policy.ListServerTlsPoliciesRequest, dict] = None,
         *,
         parent: str = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> pagers.ListServerTlsPoliciesAsyncPager:
@@ -669,7 +679,7 @@ async def list_server_tls_policies(
         location.
 
         Args:
-            request (:class:`google.cloud.network_security_v1beta1.types.ListServerTlsPoliciesRequest`):
+            request (Union[google.cloud.network_security_v1beta1.types.ListServerTlsPoliciesRequest, dict]):
                 The request object. Request used by the
                 ListServerTlsPolicies method.
             parent (:class:`str`):
@@ -740,17 +750,17 @@ async def list_server_tls_policies(
 
     async def get_server_tls_policy(
         self,
-        request: server_tls_policy.GetServerTlsPolicyRequest = None,
+        request: Union[server_tls_policy.GetServerTlsPolicyRequest, dict] = None,
         *,
         name: str = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> server_tls_policy.ServerTlsPolicy:
         r"""Gets details of a single ServerTlsPolicy.
 
         Args:
-            request (:class:`google.cloud.network_security_v1beta1.types.GetServerTlsPolicyRequest`):
+            request (Union[google.cloud.network_security_v1beta1.types.GetServerTlsPolicyRequest, dict]):
                 The request object. Request used by the
                 GetServerTlsPolicy method.
             name (:class:`str`):
@@ -817,12 +827,12 @@ async def get_server_tls_policy(
 
     async def create_server_tls_policy(
         self,
-        request: gcn_server_tls_policy.CreateServerTlsPolicyRequest = None,
+        request: Union[gcn_server_tls_policy.CreateServerTlsPolicyRequest, dict] = None,
         *,
         parent: str = None,
         server_tls_policy: gcn_server_tls_policy.ServerTlsPolicy = None,
         server_tls_policy_id: str = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation_async.AsyncOperation:
@@ -830,7 +840,7 @@ async def create_server_tls_policy(
         location.
 
         Args:
-            request (:class:`google.cloud.network_security_v1beta1.types.CreateServerTlsPolicyRequest`):
+            request (Union[google.cloud.network_security_v1beta1.types.CreateServerTlsPolicyRequest, dict]):
                 The request object. Request used by the
                 CreateServerTlsPolicy method.
             parent (:class:`str`):
@@ -926,18 +936,18 @@ async def create_server_tls_policy(
 
     async def update_server_tls_policy(
         self,
-        request: gcn_server_tls_policy.UpdateServerTlsPolicyRequest = None,
+        request: Union[gcn_server_tls_policy.UpdateServerTlsPolicyRequest, dict] = None,
         *,
         server_tls_policy: gcn_server_tls_policy.ServerTlsPolicy = None,
         update_mask: field_mask_pb2.FieldMask = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation_async.AsyncOperation:
         r"""Updates the parameters of a single ServerTlsPolicy.
 
         Args:
-            request (:class:`google.cloud.network_security_v1beta1.types.UpdateServerTlsPolicyRequest`):
+            request (Union[google.cloud.network_security_v1beta1.types.UpdateServerTlsPolicyRequest, dict]):
                 The request object. Request used by
                 UpdateServerTlsPolicy method.
             server_tls_policy (:class:`google.cloud.network_security_v1beta1.types.ServerTlsPolicy`):
@@ -1027,17 +1037,17 @@ async def update_server_tls_policy(
 
     async def delete_server_tls_policy(
         self,
-        request: server_tls_policy.DeleteServerTlsPolicyRequest = None,
+        request: Union[server_tls_policy.DeleteServerTlsPolicyRequest, dict] = None,
         *,
         name: str = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation_async.AsyncOperation:
         r"""Deletes a single ServerTlsPolicy.
 
         Args:
-            request (:class:`google.cloud.network_security_v1beta1.types.DeleteServerTlsPolicyRequest`):
+            request (Union[google.cloud.network_security_v1beta1.types.DeleteServerTlsPolicyRequest, dict]):
                 The request object. Request used by the
                 DeleteServerTlsPolicy method.
             name (:class:`str`):
@@ -1120,10 +1130,10 @@ async def delete_server_tls_policy(
 
     async def list_client_tls_policies(
         self,
-        request: client_tls_policy.ListClientTlsPoliciesRequest = None,
+        request: Union[client_tls_policy.ListClientTlsPoliciesRequest, dict] = None,
         *,
         parent: str = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> pagers.ListClientTlsPoliciesAsyncPager:
@@ -1131,7 +1141,7 @@ async def list_client_tls_policies(
         location.
 
         Args:
-            request (:class:`google.cloud.network_security_v1beta1.types.ListClientTlsPoliciesRequest`):
+            request (Union[google.cloud.network_security_v1beta1.types.ListClientTlsPoliciesRequest, dict]):
                 The request object. Request used by the
                 ListClientTlsPolicies method.
             parent (:class:`str`):
@@ -1202,17 +1212,17 @@ async def list_client_tls_policies(
 
     async def get_client_tls_policy(
         self,
-        request: client_tls_policy.GetClientTlsPolicyRequest = None,
+        request: Union[client_tls_policy.GetClientTlsPolicyRequest, dict] = None,
         *,
         name: str = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> client_tls_policy.ClientTlsPolicy:
         r"""Gets details of a single ClientTlsPolicy.
 
         Args:
-            request (:class:`google.cloud.network_security_v1beta1.types.GetClientTlsPolicyRequest`):
+            request (Union[google.cloud.network_security_v1beta1.types.GetClientTlsPolicyRequest, dict]):
                 The request object. Request used by the
                 GetClientTlsPolicy method.
             name (:class:`str`):
@@ -1278,12 +1288,12 @@ async def get_client_tls_policy(
 
     async def create_client_tls_policy(
         self,
-        request: gcn_client_tls_policy.CreateClientTlsPolicyRequest = None,
+        request: Union[gcn_client_tls_policy.CreateClientTlsPolicyRequest, dict] = None,
         *,
         parent: str = None,
         client_tls_policy: gcn_client_tls_policy.ClientTlsPolicy = None,
         client_tls_policy_id: str = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation_async.AsyncOperation:
@@ -1291,7 +1301,7 @@ async def create_client_tls_policy(
         location.
 
         Args:
-            request (:class:`google.cloud.network_security_v1beta1.types.CreateClientTlsPolicyRequest`):
+            request (Union[google.cloud.network_security_v1beta1.types.CreateClientTlsPolicyRequest, dict]):
                 The request object. Request used by the
                 CreateClientTlsPolicy method.
             parent (:class:`str`):
@@ -1386,18 +1396,18 @@ async def create_client_tls_policy(
 
     async def update_client_tls_policy(
         self,
-        request: gcn_client_tls_policy.UpdateClientTlsPolicyRequest = None,
+        request: Union[gcn_client_tls_policy.UpdateClientTlsPolicyRequest, dict] = None,
         *,
         client_tls_policy: gcn_client_tls_policy.ClientTlsPolicy = None,
         update_mask: field_mask_pb2.FieldMask = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation_async.AsyncOperation:
         r"""Updates the parameters of a single ClientTlsPolicy.
 
         Args:
-            request (:class:`google.cloud.network_security_v1beta1.types.UpdateClientTlsPolicyRequest`):
+            request (Union[google.cloud.network_security_v1beta1.types.UpdateClientTlsPolicyRequest, dict]):
                 The request object. Request used by
                 UpdateClientTlsPolicy method.
             client_tls_policy (:class:`google.cloud.network_security_v1beta1.types.ClientTlsPolicy`):
@@ -1486,17 +1496,17 @@ async def update_client_tls_policy(
 
     async def delete_client_tls_policy(
         self,
-        request: client_tls_policy.DeleteClientTlsPolicyRequest = None,
+        request: Union[client_tls_policy.DeleteClientTlsPolicyRequest, dict] = None,
         *,
         name: str = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation_async.AsyncOperation:
         r"""Deletes a single ClientTlsPolicy.
 
         Args:
-            request (:class:`google.cloud.network_security_v1beta1.types.DeleteClientTlsPolicyRequest`):
+            request (Union[google.cloud.network_security_v1beta1.types.DeleteClientTlsPolicyRequest, dict]):
                 The request object. Request used by the
                 DeleteClientTlsPolicy method.
             name (:class:`str`):
diff --git a/google/cloud/network_security_v1beta1/services/network_security/client.py b/google/cloud/network_security_v1beta1/services/network_security/client.py
index 30e7e6f..94c7338 100644
--- a/google/cloud/network_security_v1beta1/services/network_security/client.py
+++ b/google/cloud/network_security_v1beta1/services/network_security/client.py
@@ -30,6 +30,8 @@
 from google.auth.exceptions import MutualTLSChannelError  # type: ignore
 from google.oauth2 import service_account  # type: ignore
 
+OptionalRetry = Union[retries.Retry, object]
+
 from google.api_core import operation  # type: ignore
 from google.api_core import operation_async  # type: ignore
 from google.cloud.network_security_v1beta1.services.network_security import pagers
@@ -412,7 +414,7 @@ def list_authorization_policies(
         ] = None,
         *,
         parent: str = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> pagers.ListAuthorizationPoliciesPager:
@@ -498,7 +500,7 @@ def get_authorization_policy(
         request: Union[authorization_policy.GetAuthorizationPolicyRequest, dict] = None,
         *,
         name: str = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> authorization_policy.AuthorizationPolicy:
@@ -579,7 +581,7 @@ def create_authorization_policy(
         parent: str = None,
         authorization_policy: gcn_authorization_policy.AuthorizationPolicy = None,
         authorization_policy_id: str = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation.Operation:
@@ -695,7 +697,7 @@ def update_authorization_policy(
         *,
         authorization_policy: gcn_authorization_policy.AuthorizationPolicy = None,
         update_mask: field_mask_pb2.FieldMask = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation.Operation:
@@ -802,7 +804,7 @@ def delete_authorization_policy(
         ] = None,
         *,
         name: str = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation.Operation:
@@ -899,7 +901,7 @@ def list_server_tls_policies(
         request: Union[server_tls_policy.ListServerTlsPoliciesRequest, dict] = None,
         *,
         parent: str = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> pagers.ListServerTlsPoliciesPager:
@@ -981,7 +983,7 @@ def get_server_tls_policy(
         request: Union[server_tls_policy.GetServerTlsPolicyRequest, dict] = None,
         *,
         name: str = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> server_tls_policy.ServerTlsPolicy:
@@ -1060,7 +1062,7 @@ def create_server_tls_policy(
         parent: str = None,
         server_tls_policy: gcn_server_tls_policy.ServerTlsPolicy = None,
         server_tls_policy_id: str = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation.Operation:
@@ -1168,7 +1170,7 @@ def update_server_tls_policy(
         *,
         server_tls_policy: gcn_server_tls_policy.ServerTlsPolicy = None,
         update_mask: field_mask_pb2.FieldMask = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation.Operation:
@@ -1268,7 +1270,7 @@ def delete_server_tls_policy(
         request: Union[server_tls_policy.DeleteServerTlsPolicyRequest, dict] = None,
         *,
         name: str = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation.Operation:
@@ -1361,7 +1363,7 @@ def list_client_tls_policies(
         request: Union[client_tls_policy.ListClientTlsPoliciesRequest, dict] = None,
         *,
         parent: str = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> pagers.ListClientTlsPoliciesPager:
@@ -1443,7 +1445,7 @@ def get_client_tls_policy(
         request: Union[client_tls_policy.GetClientTlsPolicyRequest, dict] = None,
         *,
         name: str = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> client_tls_policy.ClientTlsPolicy:
@@ -1521,7 +1523,7 @@ def create_client_tls_policy(
         parent: str = None,
         client_tls_policy: gcn_client_tls_policy.ClientTlsPolicy = None,
         client_tls_policy_id: str = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation.Operation:
@@ -1628,7 +1630,7 @@ def update_client_tls_policy(
         *,
         client_tls_policy: gcn_client_tls_policy.ClientTlsPolicy = None,
         update_mask: field_mask_pb2.FieldMask = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation.Operation:
@@ -1727,7 +1729,7 @@ def delete_client_tls_policy(
         request: Union[client_tls_policy.DeleteClientTlsPolicyRequest, dict] = None,
         *,
         name: str = None,
-        retry: retries.Retry = gapic_v1.method.DEFAULT,
+        retry: OptionalRetry = gapic_v1.method.DEFAULT,
         timeout: float = None,
         metadata: Sequence[Tuple[str, str]] = (),
     ) -> operation.Operation:
diff --git a/google/cloud/network_security_v1beta1/services/network_security/transports/base.py b/google/cloud/network_security_v1beta1/services/network_security/transports/base.py
index 0a8f566..f690d5e 100644
--- a/google/cloud/network_security_v1beta1/services/network_security/transports/base.py
+++ b/google/cloud/network_security_v1beta1/services/network_security/transports/base.py
@@ -15,7 +15,6 @@
 #
 import abc
 from typing import Awaitable, Callable, Dict, Optional, Sequence, Union
-import packaging.version
 import pkg_resources
 
 import google.auth  # type: ignore
@@ -50,15 +49,6 @@
 except pkg_resources.DistributionNotFound:
     DEFAULT_CLIENT_INFO = gapic_v1.client_info.ClientInfo()
 
-try:
-    # google.auth.__version__ was added in 1.26.0
-    _GOOGLE_AUTH_VERSION = google.auth.__version__
-except AttributeError:
-    try:  # try pkg_resources if it is available
-        _GOOGLE_AUTH_VERSION = pkg_resources.get_distribution("google-auth").version
-    except pkg_resources.DistributionNotFound:  # pragma: NO COVER
-        _GOOGLE_AUTH_VERSION = None
-
 
 class NetworkSecurityTransport(abc.ABC):
     """Abstract transport class for NetworkSecurity."""
@@ -108,7 +98,7 @@ def __init__(
             host += ":443"
         self._host = host
 
-        scopes_kwargs = self._get_scopes_kwargs(self._host, scopes)
+        scopes_kwargs = {"scopes": scopes, "default_scopes": self.AUTH_SCOPES}
 
         # Save the scopes.
         self._scopes = scopes
@@ -141,29 +131,6 @@ def __init__(
         # Save the credentials.
         self._credentials = credentials
 
-    # TODO(busunkim): This method is in the base transport
-    # to avoid duplicating code across the transport classes. These functions
-    # should be deleted once the minimum required versions of google-auth is increased.
-
-    # TODO: Remove this function once google-auth >= 1.25.0 is required
-    @classmethod
-    def _get_scopes_kwargs(
-        cls, host: str, scopes: Optional[Sequence[str]]
-    ) -> Dict[str, Optional[Sequence[str]]]:
-        """Returns scopes kwargs to pass to google-auth methods depending on the google-auth version"""
-
-        scopes_kwargs = {}
-
-        if _GOOGLE_AUTH_VERSION and (
-            packaging.version.parse(_GOOGLE_AUTH_VERSION)
-            >= packaging.version.parse("1.25.0")
-        ):
-            scopes_kwargs = {"scopes": scopes, "default_scopes": cls.AUTH_SCOPES}
-        else:
-            scopes_kwargs = {"scopes": scopes or cls.AUTH_SCOPES}
-
-        return scopes_kwargs
-
     def _prep_wrapped_messages(self, client_info):
         # Precompute the wrapped methods.
         self._wrapped_methods = {
@@ -254,7 +221,7 @@ def close(self):
         raise NotImplementedError()
 
     @property
-    def operations_client(self) -> operations_v1.OperationsClient:
+    def operations_client(self):
         """Return the client designed to process long-running operations."""
         raise NotImplementedError()
 
diff --git a/google/cloud/network_security_v1beta1/services/network_security/transports/grpc.py b/google/cloud/network_security_v1beta1/services/network_security/transports/grpc.py
index 21b81ae..094c1da 100644
--- a/google/cloud/network_security_v1beta1/services/network_security/transports/grpc.py
+++ b/google/cloud/network_security_v1beta1/services/network_security/transports/grpc.py
@@ -121,7 +121,7 @@ def __init__(
         self._grpc_channel = None
         self._ssl_channel_credentials = ssl_channel_credentials
         self._stubs: Dict[str, Callable] = {}
-        self._operations_client = None
+        self._operations_client: Optional[operations_v1.OperationsClient] = None
 
         if api_mtls_endpoint:
             warnings.warn("api_mtls_endpoint is deprecated", DeprecationWarning)
diff --git a/google/cloud/network_security_v1beta1/services/network_security/transports/grpc_asyncio.py b/google/cloud/network_security_v1beta1/services/network_security/transports/grpc_asyncio.py
index d44b6af..435d337 100644
--- a/google/cloud/network_security_v1beta1/services/network_security/transports/grpc_asyncio.py
+++ b/google/cloud/network_security_v1beta1/services/network_security/transports/grpc_asyncio.py
@@ -21,7 +21,6 @@
 from google.api_core import operations_v1  # type: ignore
 from google.auth import credentials as ga_credentials  # type: ignore
 from google.auth.transport.grpc import SslCredentials  # type: ignore
-import packaging.version
 
 import grpc  # type: ignore
 from grpc.experimental import aio  # type: ignore
@@ -168,7 +167,7 @@ def __init__(
         self._grpc_channel = None
         self._ssl_channel_credentials = ssl_channel_credentials
         self._stubs: Dict[str, Callable] = {}
-        self._operations_client = None
+        self._operations_client: Optional[operations_v1.OperationsAsyncClient] = None
 
         if api_mtls_endpoint:
             warnings.warn("api_mtls_endpoint is deprecated", DeprecationWarning)
diff --git a/google/cloud/network_security_v1beta1/types/authorization_policy.py b/google/cloud/network_security_v1beta1/types/authorization_policy.py
index 3f933e2..25b426c 100644
--- a/google/cloud/network_security_v1beta1/types/authorization_policy.py
+++ b/google/cloud/network_security_v1beta1/types/authorization_policy.py
@@ -142,6 +142,8 @@ class Destination(proto.Message):
             class HttpHeaderMatch(proto.Message):
                 r"""Specification of HTTP header match atrributes.
 
+                .. _oneof: https://proto-plus-python.readthedocs.io/en/stable/fields.html#oneofs-mutually-exclusive-fields
+
                 Attributes:
                     regex_match (str):
                         Required. The value of the header must match
@@ -152,6 +154,7 @@ class HttpHeaderMatch(proto.Message):
                         request, use a headerMatch with headerName set
                         to Host and a regular expression that satisfies
                         the RFC2616 Host header's port specifier.
+                        This field is a member of `oneof`_ ``type``.
                     header_name (str):
                         Required. The name of the HTTP header to
                         match. For matching against the HTTP request's
diff --git a/google/cloud/network_security_v1beta1/types/tls.py b/google/cloud/network_security_v1beta1/types/tls.py
index 5029d02..99760af 100644
--- a/google/cloud/network_security_v1beta1/types/tls.py
+++ b/google/cloud/network_security_v1beta1/types/tls.py
@@ -45,15 +45,24 @@ class ValidationCA(proto.Message):
     obtain the Certificate Authority certificate to validate the
     peer certificate.
 
+    This message has `oneof`_ fields (mutually exclusive fields).
+    For each oneof, at most one member field can be set at the same time.
+    Setting any member of the oneof automatically clears all other
+    members.
+
+    .. _oneof: https://proto-plus-python.readthedocs.io/en/stable/fields.html#oneofs-mutually-exclusive-fields
+
     Attributes:
         grpc_endpoint (google.cloud.network_security_v1beta1.types.GrpcEndpoint):
             gRPC specific configuration to access the
             gRPC server to obtain the CA certificate.
+            This field is a member of `oneof`_ ``type``.
         certificate_provider_instance (google.cloud.network_security_v1beta1.types.CertificateProviderInstance):
             The certificate provider instance
             specification that will be passed to the data
             plane, which will be used to load necessary
             credential information.
+            This field is a member of `oneof`_ ``type``.
     """
 
     grpc_endpoint = proto.Field(
@@ -88,15 +97,24 @@ class CertificateProvider(proto.Message):
     to obtain the certificate and private key for peer to peer
     authentication.
 
+    This message has `oneof`_ fields (mutually exclusive fields).
+    For each oneof, at most one member field can be set at the same time.
+    Setting any member of the oneof automatically clears all other
+    members.
+
+    .. _oneof: https://proto-plus-python.readthedocs.io/en/stable/fields.html#oneofs-mutually-exclusive-fields
+
     Attributes:
         grpc_endpoint (google.cloud.network_security_v1beta1.types.GrpcEndpoint):
             gRPC specific configuration to access the
             gRPC server to obtain the cert and private key.
+            This field is a member of `oneof`_ ``type``.
         certificate_provider_instance (google.cloud.network_security_v1beta1.types.CertificateProviderInstance):
             The certificate provider instance
             specification that will be passed to the data
             plane, which will be used to load necessary
             credential information.
+            This field is a member of `oneof`_ ``type``.
     """
 
     grpc_endpoint = proto.Field(
diff --git a/noxfile.py b/noxfile.py
index f885c68..2a2001c 100644
--- a/noxfile.py
+++ b/noxfile.py
@@ -101,7 +101,7 @@ def default(session):
         "py.test",
         "--quiet",
         f"--junitxml=unit_{session.python}_sponge_log.xml",
-        "--cov=google/cloud",
+        "--cov=google",
         "--cov=tests/unit",
         "--cov-append",
         "--cov-config=.coveragerc",
@@ -175,7 +175,7 @@ def cover(session):
     test runs (not system test runs), and then erases coverage data.
     """
     session.install("coverage", "pytest-cov")
-    session.run("coverage", "report", "--show-missing", "--fail-under=99")
+    session.run("coverage", "report", "--show-missing", "--fail-under=100")
 
     session.run("coverage", "erase")
 
diff --git a/owlbot.py b/owlbot.py
deleted file mode 100644
index e4c86b9..0000000
--- a/owlbot.py
+++ /dev/null
@@ -1,83 +0,0 @@
-# Copyright 2021 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.
-
-import synthtool as s
-import synthtool.gcp as gcp
-from synthtool.languages import python
-
-# ----------------------------------------------------------------------------
-# Copy the generated client from the owl-bot staging directory
-# ----------------------------------------------------------------------------
-
-default_version = "v1beta1"
-
-for library in s.get_staging_dirs(default_version):
-    s.move(library, excludes=["setup.py", "README.rst", "docs/index.rst"])
-s.remove_staging_dirs()
-
-# ----------------------------------------------------------------------------
-# Add templated files
-# ----------------------------------------------------------------------------
-
-templated_files = gcp.CommonTemplates().py_library(microgenerator=True, cov_level=99)
-python.py_samples(skip_readmes=True)
-s.move(templated_files, excludes=[".coveragerc"]) # the microgenerator has a good coveragerc file
-
-# Remove the replacements below once https://github.com/googleapis/synthtool/pull/1188 is merged
-
-# Update googleapis/repo-automation-bots repo to main in .kokoro/*.sh files
-s.replace(".kokoro/*.sh", "repo-automation-bots/tree/master", "repo-automation-bots/tree/main")
-
-# Customize CONTRIBUTING.rst to replace master with main
-s.replace(
-    "CONTRIBUTING.rst",
-    "fetch and merge changes from upstream into master",
-    "fetch and merge changes from upstream into main",
-)
-
-s.replace(
-    "CONTRIBUTING.rst",
-    "git merge upstream/master",
-    "git merge upstream/main",
-)
-
-s.replace(
-    "CONTRIBUTING.rst",
-    """export GOOGLE_CLOUD_TESTING_BRANCH=\"master\"""",
-    """export GOOGLE_CLOUD_TESTING_BRANCH=\"main\"""",
-)
-
-s.replace(
-    "CONTRIBUTING.rst",
-    "remote \(``master``\)",
-    "remote (``main``)",
-)
-
-s.replace(
-    "CONTRIBUTING.rst",
-    "blob/master/CONTRIBUTING.rst",
-    "blob/main/CONTRIBUTING.rst",
-)
-
-s.replace(
-    "CONTRIBUTING.rst",
-    "blob/master/noxfile.py",
-    "blob/main/noxfile.py",
-)
-
-# ----------------------------------------------------------------------------
-# Run blacken session
-# ----------------------------------------------------------------------------
-
-s.shell.run(["nox", "-s", "blacken"], hide_output=False)
diff --git a/setup.py b/setup.py
index 2085d1b..e62d17e 100644
--- a/setup.py
+++ b/setup.py
@@ -22,15 +22,14 @@
 
 name = "google-cloud-network-security"
 description = "Network Security API client library"
-version = "0.3.0"
+version = "0.3.1"
 release_status = "Development Status :: 4 - Beta"
 dependencies = [
     # NOTE: Maintainers, please do not require google-api-core>=2.x.x
     # Until this issue is closed
     # https://github.com/googleapis/google-cloud-python/issues/10566
-    "google-api-core[grpc] >= 1.26.0, <3.0.0dev",
+    "google-api-core[grpc] >= 1.28.0, <3.0.0dev",
     "proto-plus >= 1.15.0",
-    "packaging >= 14.3",
 ]
 
 package_root = os.path.abspath(os.path.dirname(__file__))
diff --git a/testing/constraints-3.6.txt b/testing/constraints-3.6.txt
index 3f7f11e..1e3ec8b 100644
--- a/testing/constraints-3.6.txt
+++ b/testing/constraints-3.6.txt
@@ -4,7 +4,5 @@
 # Pin the version to the lower bound.
 # e.g., if setup.py has "google-cloud-foo >= 1.14.0, < 2.0.0dev",
 # Then this file should have google-cloud-foo==1.14.0
-google-api-core==1.26.0
+google-api-core==1.28.0
 proto-plus==1.15.0
-packaging==14.3
-google-auth==1.24.0  # TODO: remove when google-auth>=1.25.0 is transitively required through google-api-core
\ No newline at end of file
diff --git a/tests/unit/gapic/network_security_v1beta1/test_network_security.py b/tests/unit/gapic/network_security_v1beta1/test_network_security.py
index 5ca3ffe..a18f7cd 100644
--- a/tests/unit/gapic/network_security_v1beta1/test_network_security.py
+++ b/tests/unit/gapic/network_security_v1beta1/test_network_security.py
@@ -15,7 +15,6 @@
 #
 import os
 import mock
-import packaging.version
 
 import grpc
 from grpc.experimental import aio
@@ -43,9 +42,6 @@
 )
 from google.cloud.network_security_v1beta1.services.network_security import pagers
 from google.cloud.network_security_v1beta1.services.network_security import transports
-from google.cloud.network_security_v1beta1.services.network_security.transports.base import (
-    _GOOGLE_AUTH_VERSION,
-)
 from google.cloud.network_security_v1beta1.types import authorization_policy
 from google.cloud.network_security_v1beta1.types import (
     authorization_policy as gcn_authorization_policy,
@@ -67,20 +63,6 @@
 import google.auth
 
 
-# TODO(busunkim): Once google-auth >= 1.25.0 is required transitively
-# through google-api-core:
-# - Delete the auth "less than" test cases
-# - Delete these pytest markers (Make the "greater than or equal to" tests the default).
-requires_google_auth_lt_1_25_0 = pytest.mark.skipif(
-    packaging.version.parse(_GOOGLE_AUTH_VERSION) >= packaging.version.parse("1.25.0"),
-    reason="This test requires google-auth < 1.25.0",
-)
-requires_google_auth_gte_1_25_0 = pytest.mark.skipif(
-    packaging.version.parse(_GOOGLE_AUTH_VERSION) < packaging.version.parse("1.25.0"),
-    reason="This test requires google-auth >= 1.25.0",
-)
-
-
 def client_cert_source_callback():
     return b"cert bytes", b"key bytes"
 
@@ -237,7 +219,7 @@ def test_network_security_client_client_options(
     options = client_options.ClientOptions(api_endpoint="squid.clam.whelk")
     with mock.patch.object(transport_class, "__init__") as patched:
         patched.return_value = None
-        client = client_class(client_options=options)
+        client = client_class(transport=transport_name, client_options=options)
         patched.assert_called_once_with(
             credentials=None,
             credentials_file=None,
@@ -254,7 +236,7 @@ def test_network_security_client_client_options(
     with mock.patch.dict(os.environ, {"GOOGLE_API_USE_MTLS_ENDPOINT": "never"}):
         with mock.patch.object(transport_class, "__init__") as patched:
             patched.return_value = None
-            client = client_class()
+            client = client_class(transport=transport_name)
             patched.assert_called_once_with(
                 credentials=None,
                 credentials_file=None,
@@ -271,7 +253,7 @@ def test_network_security_client_client_options(
     with mock.patch.dict(os.environ, {"GOOGLE_API_USE_MTLS_ENDPOINT": "always"}):
         with mock.patch.object(transport_class, "__init__") as patched:
             patched.return_value = None
-            client = client_class()
+            client = client_class(transport=transport_name)
             patched.assert_called_once_with(
                 credentials=None,
                 credentials_file=None,
@@ -300,7 +282,7 @@ def test_network_security_client_client_options(
     options = client_options.ClientOptions(quota_project_id="octopus")
     with mock.patch.object(transport_class, "__init__") as patched:
         patched.return_value = None
-        client = client_class(client_options=options)
+        client = client_class(transport=transport_name, client_options=options)
         patched.assert_called_once_with(
             credentials=None,
             credentials_file=None,
@@ -369,7 +351,7 @@ def test_network_security_client_mtls_env_auto(
         )
         with mock.patch.object(transport_class, "__init__") as patched:
             patched.return_value = None
-            client = client_class(client_options=options)
+            client = client_class(transport=transport_name, client_options=options)
 
             if use_client_cert_env == "false":
                 expected_client_cert_source = None
@@ -411,7 +393,7 @@ def test_network_security_client_mtls_env_auto(
                         expected_client_cert_source = client_cert_source_callback
 
                     patched.return_value = None
-                    client = client_class()
+                    client = client_class(transport=transport_name)
                     patched.assert_called_once_with(
                         credentials=None,
                         credentials_file=None,
@@ -433,7 +415,7 @@ def test_network_security_client_mtls_env_auto(
                 return_value=False,
             ):
                 patched.return_value = None
-                client = client_class()
+                client = client_class(transport=transport_name)
                 patched.assert_called_once_with(
                     credentials=None,
                     credentials_file=None,
@@ -464,7 +446,7 @@ def test_network_security_client_client_options_scopes(
     options = client_options.ClientOptions(scopes=["1", "2"],)
     with mock.patch.object(transport_class, "__init__") as patched:
         patched.return_value = None
-        client = client_class(client_options=options)
+        client = client_class(transport=transport_name, client_options=options)
         patched.assert_called_once_with(
             credentials=None,
             credentials_file=None,
@@ -495,7 +477,7 @@ def test_network_security_client_client_options_credentials_file(
     options = client_options.ClientOptions(credentials_file="credentials.json")
     with mock.patch.object(transport_class, "__init__") as patched:
         patched.return_value = None
-        client = client_class(client_options=options)
+        client = client_class(transport=transport_name, client_options=options)
         patched.assert_called_once_with(
             credentials=None,
             credentials_file="credentials.json",
@@ -4624,7 +4606,6 @@ def test_network_security_base_transport():
         transport.operations_client
 
 
-@requires_google_auth_gte_1_25_0
 def test_network_security_base_transport_with_credentials_file():
     # Instantiate the base transport with a credentials file
     with mock.patch.object(
@@ -4645,26 +4626,6 @@ def test_network_security_base_transport_with_credentials_file():
         )
 
 
-@requires_google_auth_lt_1_25_0
-def test_network_security_base_transport_with_credentials_file_old_google_auth():
-    # Instantiate the base transport with a credentials file
-    with mock.patch.object(
-        google.auth, "load_credentials_from_file", autospec=True
-    ) as load_creds, mock.patch(
-        "google.cloud.network_security_v1beta1.services.network_security.transports.NetworkSecurityTransport._prep_wrapped_messages"
-    ) as Transport:
-        Transport.return_value = None
-        load_creds.return_value = (ga_credentials.AnonymousCredentials(), None)
-        transport = transports.NetworkSecurityTransport(
-            credentials_file="credentials.json", quota_project_id="octopus",
-        )
-        load_creds.assert_called_once_with(
-            "credentials.json",
-            scopes=("https://www.googleapis.com/auth/cloud-platform",),
-            quota_project_id="octopus",
-        )
-
-
 def test_network_security_base_transport_with_adc():
     # Test the default credentials are used if credentials and credentials_file are None.
     with mock.patch.object(google.auth, "default", autospec=True) as adc, mock.patch(
@@ -4676,7 +4637,6 @@ def test_network_security_base_transport_with_adc():
         adc.assert_called_once()
 
 
-@requires_google_auth_gte_1_25_0
 def test_network_security_auth_adc():
     # If no credentials are provided, we should use ADC credentials.
     with mock.patch.object(google.auth, "default", autospec=True) as adc:
@@ -4689,18 +4649,6 @@ def test_network_security_auth_adc():
         )
 
 
-@requires_google_auth_lt_1_25_0
-def test_network_security_auth_adc_old_google_auth():
-    # If no credentials are provided, we should use ADC credentials.
-    with mock.patch.object(google.auth, "default", autospec=True) as adc:
-        adc.return_value = (ga_credentials.AnonymousCredentials(), None)
-        NetworkSecurityClient()
-        adc.assert_called_once_with(
-            scopes=("https://www.googleapis.com/auth/cloud-platform",),
-            quota_project_id=None,
-        )
-
-
 @pytest.mark.parametrize(
     "transport_class",
     [
@@ -4708,7 +4656,6 @@ def test_network_security_auth_adc_old_google_auth():
         transports.NetworkSecurityGrpcAsyncIOTransport,
     ],
 )
-@requires_google_auth_gte_1_25_0
 def test_network_security_transport_auth_adc(transport_class):
     # If credentials and host are not provided, the transport class should use
     # ADC credentials.
@@ -4722,26 +4669,6 @@ def test_network_security_transport_auth_adc(transport_class):
         )
 
 
-@pytest.mark.parametrize(
-    "transport_class",
-    [
-        transports.NetworkSecurityGrpcTransport,
-        transports.NetworkSecurityGrpcAsyncIOTransport,
-    ],
-)
-@requires_google_auth_lt_1_25_0
-def test_network_security_transport_auth_adc_old_google_auth(transport_class):
-    # If credentials and host are not provided, the transport class should use
-    # ADC credentials.
-    with mock.patch.object(google.auth, "default", autospec=True) as adc:
-        adc.return_value = (ga_credentials.AnonymousCredentials(), None)
-        transport_class(quota_project_id="octopus")
-        adc.assert_called_once_with(
-            scopes=("https://www.googleapis.com/auth/cloud-platform",),
-            quota_project_id="octopus",
-        )
-
-
 @pytest.mark.parametrize(
     "transport_class,grpc_helpers",
     [