diff --git a/.librarian/generator-input/client-post-processing/unique-grafeas-client.yaml b/.librarian/generator-input/client-post-processing/unique-grafeas-client.yaml
index 10783989088a..065363d674ad 100644
--- a/.librarian/generator-input/client-post-processing/unique-grafeas-client.yaml
+++ b/.librarian/generator-input/client-post-processing/unique-grafeas-client.yaml
@@ -1957,13 +1957,13 @@ replacements:
           def __init__(
               self,
               *,
-              transport: Union[str, GrafeasTransport] = None,
+              transport: Optional[Union[str, GrafeasTransport]] = None,
               credentials: Optional[ga_credentials.Credentials] = None,
           ) -> None:
               """Instantiate the grafeas client.
 
               Args:
-                  transport (Union[str, ~.GrafeasTransport]): The
+                  transport (Optional[Union[str, ~.GrafeasTransport]]): The
                       transport to use.
                   credentials (Optional[google.auth.credentials.Credentials]): The
                       authorization credentials to attach to requests. These
diff --git a/packages/grafeas/grafeas/grafeas_v1/services/grafeas/client.py b/packages/grafeas/grafeas/grafeas_v1/services/grafeas/client.py
index f8dc481d17f5..1c2a69c405ee 100644
--- a/packages/grafeas/grafeas/grafeas_v1/services/grafeas/client.py
+++ b/packages/grafeas/grafeas/grafeas_v1/services/grafeas/client.py
@@ -359,13 +359,13 @@ def parse_common_location_path(path: str) -> Dict[str, str]:
     def __init__(
         self,
         *,
-        transport: Union[str, GrafeasTransport] = None,
+        transport: Optional[Union[str, GrafeasTransport]] = None,
         credentials: Optional[ga_credentials.Credentials] = None,
     ) -> None:
         """Instantiate the grafeas client.
 
         Args:
-            transport (Union[str, ~.GrafeasTransport]): The
+            transport (Optional[Union[str, ~.GrafeasTransport]]): The
                 transport to use.
             credentials (Optional[google.auth.credentials.Credentials]): The
                 authorization credentials to attach to requests. These