Fix mltable load of registered data asset: restore DataVersionEntity.additional_properties

[saanikaguptamicrosoft]

Notes

• Prod regression from: Azure AI ML to TSP #45389
  The dataset_dataplane TypeSpec (hybrid) migration (Azure AI ML to TSP #45389) dropped the msrest additional_properties attribute from DataVersionEntity. The mltable package's local data-asset resolution path (MLClient.jobs._dataset_dataplane_operations._operation.get) reads additional_properties['isV2'|'legacyDataflow'], so loading a registered MLTable data asset via mltable.load('azureml://.../data//versions/') raised AttributeError. Restored the attribute as a regeneration-safe compat shim in models/_patch.py returning the un-modeled wire keys. Wire contract unchanged.

Testing

• Before:

• After: SDK Samples Run generated from 6619649 azureml-examples#4087

The failing two mltable notebook samples are succeeding now

Description

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[Copilot]

Pull request overview

Restores MLTable loading compatibility after the dataset dataplane TypeSpec migration.

Changes:

• Adds an additional_properties compatibility shim.
• Adds regression tests for modeled and unmodeled fields.
• Documents the fix in the changelog.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
models/_patch.py	Restores access to unmodeled wire properties.
test_dataset_dataplane_additional_properties.py	Tests compatibility behavior and edge cases.
CHANGELOG.md	Records the MLTable loading fix.