feat(storagetransfer): update the api

#### storagetransfer:v1

The following keys were added:
- schemas.TransferOptions.properties.overwriteWhen.type (Total Keys: 1)

Author: yoshi-automation

docs/dyn/storagetransfer_v1.projects.agentPools.html

@@ -152,7 +152,7 @@ <h3>Method Details</h3>
 Returns:
   An object of the form:
 
-    { # A generic empty message that you can re-use to avoid defining duplicated empty messages in your APIs. A typical example is to use it as the request or the response type of an API method. For instance: service Foo { rpc Bar(google.protobuf.Empty) returns (google.protobuf.Empty); } The JSON representation for `Empty` is empty JSON object `{}`.
+    { # A generic empty message that you can re-use to avoid defining duplicated empty messages in your APIs. A typical example is to use it as the request or the response type of an API method. For instance: service Foo { rpc Bar(google.protobuf.Empty) returns (google.protobuf.Empty); }
 }</pre>
 </div>