What does this implement/fix? Explain your changes.

This PR removes an obsolete attribute in PropertyObejct

Does this close any currently open issues?

No

Any other comments?

The attribute is obsolete, not honored by the runtime, and causes problems with Unity.

Checklist

Check all those that are applicable and complete.

• Make sure to include one or more tests for your change
• If an enhancement PR, please create docs and at best an example
• Add yourself to AUTHORS
• Updated the CHANGELOG