[Add] uml-like metadata decorators on the model; fixes #27

[samatstariongroup]

Summary

Implements #27 — add UML-like metadata to the model classes and properties (as done in the COMET-SDK / uml4net) so that ReqIF metamodel relationships are self-documenting.

Two decorators are introduced under ReqIFSharp/Decorators, modelled on uml4net's Decorators but reduced to what ReqIF actually models and prefixed with ReqIf to avoid collisions (e.g. with NUnit.Framework.PropertyAttribute):

• ReqIfClassAttribute (used as [ReqIfClass(...)]) — name (the ReqIF metaclass / XML element name) and isAbstract.
• ReqIfPropertyAttribute (used as [ReqIfProperty(...)]) — aggregation (containment vs reference), lowerValue/upperValue multiplicity, isOrdered, isReadOnly, isDerived, isDerivedUnion, isUnique, defaultValue.
• AggregationKind enum (None / Shared / Composite).

[ReqIfClass] is applied to all 54 model classes and [ReqIfProperty] to every metamodel property, with multiplicity and aggregation values sourced from the embedded reqif.xsd. The decorators live in the ReqIFSharp namespace, so no extra using is needed on the model classes.

Per the issue scope, uml4net's Implements / Subsetted / RedefinedBy / RedefinedProperty decorators were not ported — ReqIFSharp has no interfaces or UML generalization-sets to attach them to. An xmiId field was also omitted (ReqIFSharp does not round-trip XMI).

Explicit arguments at every use-site

Every decorator usage passes all constructor arguments explicitly — including the optional ones that would otherwise fall back to defaults — so the metadata is fully self-documenting where it is applied:

[ReqIfClass(name: "SPEC-OBJECT", isAbstract: false)]
public class SpecObject : SpecElementWithAttributes

[ReqIfProperty(aggregation: AggregationKind.None, lowerValue: 1, upperValue: 1, isOrdered: false, isReadOnly: false, isDerived: false, isDerivedUnion: false, isUnique: true, defaultValue: null)]
public SpecObjectType Type { get; set; }

Concrete classes carry isAbstract: false and abstract bases isAbstract: true; all 87 [ReqIfProperty] usages list the full nine-argument set.

Completeness guard

ModelMetadataTestFixture is a reflection-driven test that fails if any model class or metamodel property is left undecorated, or if multiplicity is inconsistent (Upper >= Lower, Upper >= 1). Container back-references (e.g. DocumentRoot, ReqIFContent, Owner) and polymorphic convenience accessors (ObjectValue, the base Type/Definition aliases) are in a documented exclusion list. This keeps future model additions honest.

(Note: explicitness itself cannot be asserted by reflection — explicitly-passed default arguments and omitted ones compile to identical attribute metadata — so it is maintained as a source convention.)

Verification

• dotnet build ReqIFSharp.sln -c Release — 0 warnings / 0 errors on netstandard2.0.
• dotnet test ReqIFSharp.sln — 376 tests pass (292 core incl. 10 new decorator tests, 84 extensions).
• The decorators are inert metadata; (de)serialization behaviour is unchanged.

Notes

• 48 model files annotated; 3 new decorator source files (ReqIfClassAttribute, ReqIfPropertyAttribute, AggregationKind); 3 new test fixtures.
• No .csproj/version changes.
• The ReqIf prefix on both decorators avoids the NUnit.Framework.PropertyAttribute collision entirely, so no test-side using alias is required.

[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
100.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud