diff --git a/google/cloud/functions_v1/types/functions.py b/google/cloud/functions_v1/types/functions.py
index 6dae135..eb2e29e 100644
--- a/google/cloud/functions_v1/types/functions.py
+++ b/google/cloud/functions_v1/types/functions.py
@@ -77,8 +77,12 @@ class CloudFunction(proto.Message):
             The source repository where a function is hosted.
         source_upload_url (str):
             The Google Cloud Storage signed URL used for source
-            uploading, generated by
-            [google.cloud.functions.v1.GenerateUploadUrl][]
+            uploading, generated by calling
+            [google.cloud.functions.v1.GenerateUploadUrl].
+
+            The signature is validated on write methods {Create, Update}
+            The signature is stripped from the Function object on read
+            methods {Get, List}
         https_trigger (google.cloud.functions_v1.types.HttpsTrigger):
             An HTTPS endpoint type of source that can be
             triggered via URL.