[main] [Possible Break] Removed Tags[] from ITelemetryItem as this was breaking later versions of TypeScript by using the intersection type instead of union type for tags property #2258

[siyuniu-ms]

for #2258

[MSNev]

This doesn't look correct... Let me try and repo locally to see the errors.

[MSNev]

Ok, looking at the usage a bit deeper and the returned error message, I think we do the following

• Remove the Tags[] completely so it's just defined as tags?: Tags; as during the serialization process in Serializer.ts we process this field with the _serializeStringMap and if that encounters an "error" it will actually report it as an error (which is what would happen if they do actually pass an incomplete array).
• Add some release notes about this possible breaking change, at the very least lets call this out in the "name" of this PR, so if someone looks at the history it will be obvious
• Leave the current "default" initializations as [] as it "seems" happy about that and the serialization is working with it -- even though technically they should be objects.

As this change will only affect npm users and the correct "typing" is really Tags anyway along with the next release being 4.1.0 its a good time to break anyone how might be trying to pass an array (which they shouldn't).

I've already checked the 1DS code with this change and it complies as well.

[MSNev]

There are a couple of references the tags[] in the API.md

And can you also put a placeholder in the RELEASES.md so that we don't forget about this potential breaking change. I'll update the title of this PR