Adding external reference to PlannerTaskDetails results in dangling name exception

Describe the bug

I am using the latest version of the library, and I'm trying to add some links to PlannerTaskDetails.
Given the PlannerExternalReference is not generated for the library, I created my own record that matches the documentation ( https://learn.microsoft.com/en-us/graph/api/resources/plannerexternalreferences?view=graph-rest-1.0 besides the type, which seems wrong and doesn't match up with the explorer so I replace that with microsoft.graph.plannerExternalReference).

I have a list of URLs, so on my details => plannerExternalReferences I then call setAdditionalData with a map of String, and my PlannerExternalReference record, where the String is my url partially escaped in the same manner in the documentation.

Running this code results in an exception in the form of: dangling name https%3A//contoso%2Esharepoint%2Ecom/teams/agile/documents/AnnualReport%2Epptx

Expected behavior

To have reference(s) added to my task.

How to reproduce

Mentione in the description

SDK Version

6.55.0

Latest version known to work for scenario above?

No response

Known Workarounds

No response

Debug output

</details>


### Configuration

_No response_

### Other information

_No response_

Start by reproducing the PlannerTaskDetails to plannerExternalReferences flow described for SDK 6.55.0, including setAdditionalData and the custom PlannerExternalReference record. Trace how the escaped URL is handled and confirm that adding one or more references completes without the dangling name exception and produces the expected request data.