Help Needed, GameLift server SKD 3.x Unreal Engine StartbackFill method documentation is very unclear

As mentioned in the below documentation, onUpdateGameSession method will be called when you initiate match backfill requests in your game.

https://docs.aws.amazon.com/gamelift/latest/flexmatchguide/match-backfill.html#match-backfill-server-data

For the startMatchBackfill operation, we currently have example for this using the JavaScript SDK...and not using the C++ as of now in the public facing documentation.

https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/GameLift.html#startMatchBackfill-property:~:text=Calling%20the%20startMatchBackfill%20operation

You can also reach out to the AWS support team for more information on your specific usecase/requirement.

Note, the previous answer linked to the AWS SDK not the Amazon GameLift Server SDK. To ensure no confusion, this is our public documentation for the 3.x Server SDK Actions w/ Unreal Engine: https://docs.aws.amazon.com/gamelift/latest/developerguide/integration-server-sdk-unreal-ref-actions.html#integration-server-sdk-unreal-ref-startmatchbackfill

We also have some documentation on integrating with Unreal that includes code snippets for other Server SDK APIs (same syntax): https://docs.aws.amazon.com/gamelift/latest/developerguide/integration-engines-setup-unreal.html#integration-engines-setup-unreal-code