New Element Individuals to handle NONE and NOASSERTION scenarios for the 'to' property of Relationships

[sbarnum]

Addresses #527

[kestewart]

Thanks for pulling this together Sean. Looks good to me.

[goneall]

This looks good to me - The description of the NoAssertion captured all the cases I was looking for.

Thanks @sbarnum

[maxhbr]

Added some more explanation, especially that [Element1, NONE] is not allowed. We should make that even more explicit so that validation also catches that.

There is also the case of a Relationship with from=NOASSERTION, relationshipType="ancestorOf", and to=Element1. This should also be explained or should be disallowed. Same for NONE.

[maxhbr]

I disagree that this is the right direction. I think a to relationship towards an empty list, together with relationship completeness, is a better way to express that information.

[kestewart]

Discussion is we should document from migration guide, how to go this for 3.0. Concern is this with completeness is going to cause more confusion than it resolves. Let's document it, and then decide which PR to apply. ( Documenting Empty list is ok with completeness indicator.. vs. adding this in again)

[goneall]

Decided to move this to post RC2 and go with the existing solution using the completness property for RC2.

[kestewart]

Discussed #623 with @JPEWdev and agreed we're going to merge it. We're going to raise this in next tech call.

[goneall]

From tech call on 2 April 2024: agreed to rename None and NoAssertion to NoneElement and NoAssertionElement resp.

[goneall]

Per tech call on 2 April 2024 -

[goneall]

@maxhbr - I believe this matches our discussion on the tech call - please re-review

The review is stale