5.56.0 breaks ExternalConnectors.DisplayTemplate.Layout with UntypedNode

[jasonjoh]

Describe the bug

Code that worked and compiled fine before to set a display template on an ExternalConnection now gives the error:

C:\Source\Repos\msgraph-sample-github-connector-dotnet\src\Services\SearchConnectorService.cs(154,29): error CS0117: 'UntypedNode' does not contain a definition for 'AdditionalData' [C:\Source\Re
pos\msgraph-sample-github-connector-dotnet\src\GitHubConnector.csproj]

Expected behavior

Code should continue to compile and work.

How to reproduce

Sample that repros error: https://github.com/microsoftgraph/msgraph-sample-github-connector-dotnet

Relevant line: https://github.com/microsoftgraph/msgraph-sample-github-connector-dotnet/blob/20d80700de852245edb16c44a73cb2ed53d436b8/src/Services/SearchConnectorService.cs#L154

SDK Version

5.56.0

Latest version known to work for scenario above?

5.55.0

Known Workarounds

No response

Debug output

Click to expand log

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### Configuration

_No response_

### Other information

_No response_