[2527] Export chained connector ends and the interface keyword

[HuiJun]

Symptom

Exporting a model containing an interface whose ends are feature chains produces invalid SysML v2 text. For the Batmobile template:

// reference
interface bat2eng : PowerInterface connect battery.powerPort to batmobileEngine.enginePort;
// exported
connection bat2eng : PowerInterface connect  to ;

Both ends are dropped, and the InterfaceUsage is exported with the connection keyword.

Root cause

• The two end PortUsages each own a ReferenceSubsetting whose chain Feature (two FeatureChainings) is stored only as ownedRelatedElement; referencedFeature is not set. SysMLElementSerializer.appendOwnedReferenceSubsetting reads getReferencedFeature() only, gets null and emits nothing. Such models exist in the wild (templates and projects created before the importer/tools set referencedFeature for owned chains).
• caseConnectionUsage hard-codes connection and is also used for InterfaceUsage, whose keyword is mandatory in the grammar (interface).

Fix

• appendOwnedReferenceSubsetting resolves the referenced feature through a new resolveReferencedFeature(ReferenceSubsetting) helper: getReferencedFeature() when set, otherwise the owned non-proxy Feature with a non-empty ownedFeatureChaining in getOwnedRelatedElement() (which is what KerML requires referencedFeature to be for an owned chain). Rendering is unchanged (appendFeatureChain / deresolved name).
• caseConnectionUsage always emits the keyword for an InterfaceUsage (via SysMLKeywordSwitch, i.e. interface), and keeps emitting connection only when a plain ConnectionUsage has a declaration, value or body. SysMLKeywordSwitch has no caseConnectionUsage, so it is deliberately not used for plain connections.

Not changed: the mutation services that build chained ends (setReferencedFeature call sites) were not modified; the exporter now tolerates both shapes, and setting referencedFeature at creation time can be addressed separately.

Tests

• SysMLElementSerializerTest: new interfaceUsageWithChainedEndsWithoutReferencedFeature (chain only in ownedRelatedElement); existing InterfaceUsage expectations updated from connection to interface.
• ImportExportTests: new checkInterfaceUsageWithChainedEnd round trip.
• CHANGELOG.adoc entry added.

Closes: #2527

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[AxelRICHARD]

Hello,

Thank your for providing this PR.
Could you also sign the Eclipse Contributor Agreement (ECA) https://www.eclipse.org/legal/eca/ please ? I won't be able to merge the PR if you don't sign it, because SysON is a project of the Eclipse Foundation.

If this PR is related to #2264 and #2275 as it seems to be (you mentioned them in the changelog), it means that the original issues must be re-opened first, then you will have to explain why on those issues.

Then I will perform a review.

Thank you for your understanding.

Regards,

[HuiJun]

Hi Axel! Sorry for the delay, but I'm actually contributing to open source according to my organization's approval, and if we get into any kind of legal review situation, it's just going to drag this on forever. I think at this point, maybe the fastest thing to do would be to disown any of the code in this PR, and let you do whatever you wish with it. We'd really like to see this get it, but let me know if we're going to have to take the long route. Thank you.

[AxelRICHARD]

Hi Axel! Sorry for the delay, but I'm actually contributing to open source according to my organization's approval, and if we get into any kind of legal review situation, it's just going to drag this on forever. I think at this point, maybe the fastest thing to do would be to disown any of the code in this PR, and let you do whatever you wish with it. We'd really like to see this get it, but let me know if we're going to have to take the long route. Thank you.

Hello,
Here is my proposal: please take into account all my remarks except the one about the ECA.
When the PR will be ok, I will close it and reopen a new one in my own name, with your consent.
Is it ok for you?
Regards,

[HuiJun]

As for closing and re-opening, absolutely no issues with that whatsoever. Sorry for the confusion about the related issue and pr. #2264 reported the same symptom (connection interface1 connect to ;) for an interface created in the diagram editor, and was fixed and closed by PR #2275 (merged July, commit 288a060). That fix handles ends whose ReferenceSubsetting.referencedFeature is set.

I've updated to PR to only reference the open issue for which this PR is targeting. Otherwise, this PR should be ready for review.

[AxelRICHARD]

@HuiJun Please also change the commit message and the changelog.

[HuiJun]

Done

[AxelRICHARD]

Close this pull request, it has been replaced by #2545
@HuiJun thank you!