diff --git a/proto-google-cloud-functions-v1/src/main/java/com/google/cloud/functions/v1/CloudFunction.java b/proto-google-cloud-functions-v1/src/main/java/com/google/cloud/functions/v1/CloudFunction.java
index 33d2374d..824f91d5 100644
--- a/proto-google-cloud-functions-v1/src/main/java/com/google/cloud/functions/v1/CloudFunction.java
+++ b/proto-google-cloud-functions-v1/src/main/java/com/google/cloud/functions/v1/CloudFunction.java
@@ -1022,7 +1022,10 @@ public com.google.cloud.functions.v1.SourceRepositoryOrBuilder getSourceReposito
    *
    * <pre>
    * The Google Cloud Storage signed URL used for source uploading, generated
-   * by [google.cloud.functions.v1.GenerateUploadUrl][]
+   * 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}
    * </pre>
    *
    * <code>string source_upload_url = 16;</code>
@@ -1037,7 +1040,10 @@ public boolean hasSourceUploadUrl() {
    *
    * <pre>
    * The Google Cloud Storage signed URL used for source uploading, generated
-   * by [google.cloud.functions.v1.GenerateUploadUrl][]
+   * 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}
    * </pre>
    *
    * <code>string source_upload_url = 16;</code>
@@ -1065,7 +1071,10 @@ public java.lang.String getSourceUploadUrl() {
    *
    * <pre>
    * The Google Cloud Storage signed URL used for source uploading, generated
-   * by [google.cloud.functions.v1.GenerateUploadUrl][]
+   * 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}
    * </pre>
    *
    * <code>string source_upload_url = 16;</code>
@@ -3462,7 +3471,10 @@ public com.google.cloud.functions.v1.SourceRepositoryOrBuilder getSourceReposito
      *
      * <pre>
      * The Google Cloud Storage signed URL used for source uploading, generated
-     * by [google.cloud.functions.v1.GenerateUploadUrl][]
+     * 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}
      * </pre>
      *
      * <code>string source_upload_url = 16;</code>
@@ -3478,7 +3490,10 @@ public boolean hasSourceUploadUrl() {
      *
      * <pre>
      * The Google Cloud Storage signed URL used for source uploading, generated
-     * by [google.cloud.functions.v1.GenerateUploadUrl][]
+     * 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}
      * </pre>
      *
      * <code>string source_upload_url = 16;</code>
@@ -3507,7 +3522,10 @@ public java.lang.String getSourceUploadUrl() {
      *
      * <pre>
      * The Google Cloud Storage signed URL used for source uploading, generated
-     * by [google.cloud.functions.v1.GenerateUploadUrl][]
+     * 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}
      * </pre>
      *
      * <code>string source_upload_url = 16;</code>
@@ -3536,7 +3554,10 @@ public com.google.protobuf.ByteString getSourceUploadUrlBytes() {
      *
      * <pre>
      * The Google Cloud Storage signed URL used for source uploading, generated
-     * by [google.cloud.functions.v1.GenerateUploadUrl][]
+     * 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}
      * </pre>
      *
      * <code>string source_upload_url = 16;</code>
@@ -3558,7 +3579,10 @@ public Builder setSourceUploadUrl(java.lang.String value) {
      *
      * <pre>
      * The Google Cloud Storage signed URL used for source uploading, generated
-     * by [google.cloud.functions.v1.GenerateUploadUrl][]
+     * 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}
      * </pre>
      *
      * <code>string source_upload_url = 16;</code>
@@ -3578,7 +3602,10 @@ public Builder clearSourceUploadUrl() {
      *
      * <pre>
      * The Google Cloud Storage signed URL used for source uploading, generated
-     * by [google.cloud.functions.v1.GenerateUploadUrl][]
+     * 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}
      * </pre>
      *
      * <code>string source_upload_url = 16;</code>
diff --git a/proto-google-cloud-functions-v1/src/main/java/com/google/cloud/functions/v1/CloudFunctionOrBuilder.java b/proto-google-cloud-functions-v1/src/main/java/com/google/cloud/functions/v1/CloudFunctionOrBuilder.java
index 0d084ab8..58a80df7 100644
--- a/proto-google-cloud-functions-v1/src/main/java/com/google/cloud/functions/v1/CloudFunctionOrBuilder.java
+++ b/proto-google-cloud-functions-v1/src/main/java/com/google/cloud/functions/v1/CloudFunctionOrBuilder.java
@@ -158,7 +158,10 @@ public interface CloudFunctionOrBuilder
    *
    * <pre>
    * The Google Cloud Storage signed URL used for source uploading, generated
-   * by [google.cloud.functions.v1.GenerateUploadUrl][]
+   * 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}
    * </pre>
    *
    * <code>string source_upload_url = 16;</code>
@@ -171,7 +174,10 @@ public interface CloudFunctionOrBuilder
    *
    * <pre>
    * The Google Cloud Storage signed URL used for source uploading, generated
-   * by [google.cloud.functions.v1.GenerateUploadUrl][]
+   * 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}
    * </pre>
    *
    * <code>string source_upload_url = 16;</code>
@@ -184,7 +190,10 @@ public interface CloudFunctionOrBuilder
    *
    * <pre>
    * The Google Cloud Storage signed URL used for source uploading, generated
-   * by [google.cloud.functions.v1.GenerateUploadUrl][]
+   * 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}
    * </pre>
    *
    * <code>string source_upload_url = 16;</code>
diff --git a/proto-google-cloud-functions-v1/src/main/proto/google/cloud/functions/v1/functions.proto b/proto-google-cloud-functions-v1/src/main/proto/google/cloud/functions/v1/functions.proto
index aa3dd5de..6523c7db 100644
--- a/proto-google-cloud-functions-v1/src/main/proto/google/cloud/functions/v1/functions.proto
+++ b/proto-google-cloud-functions-v1/src/main/proto/google/cloud/functions/v1/functions.proto
@@ -1,4 +1,4 @@
-// Copyright 2020 Google LLC
+// 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.
@@ -243,7 +243,11 @@ message CloudFunction {
     SourceRepository source_repository = 4;
 
     // The Google Cloud Storage signed URL used for source uploading, generated
-    // by [google.cloud.functions.v1.GenerateUploadUrl][]
+    // 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}
     string source_upload_url = 16;
   }