ST6RI-964 The operation Type.getOwnedDisjoining() always returns the empty list

[seidewitz]

This PR fixes a bug causing Type.getOwnedDisjoining() to always return the empty list and, so, also resolves Issue #790.

Background

In the following KerML model:

package Disjoining {
	private import SequenceFunctions::size;
	
    classifier A;
    classifier B disjoint from A;
    classifier C disjoint from A, B;
    
    feature b = size((B meta KerML::Classifier).ownedDisjoining);
    feature c = size((C meta KerML::Classifier).ownedDisjoining);
}

features b and c should evaluate to 1 and 2, respectively. Instead, they both previously evaluated to 0.

Change

The root cause was an error in Type_ownedDisjoining_SettingDelegate.basicGet():

	@Override
	protected EList<?> basicGet(InternalEObject owner) {
		EList<Disjoining> disjoinings = new NonNotifyingEObjectEList<>(Disjoining.class, owner, eStructuralFeature.getFeatureID());
		((Type)owner).getOwnedRelationship().stream().
			filter(Disjoining.class::isInstance).
			map(Disjoining.class::cast).
			filter(gen->gen.getTypeDisjoined() == this).
			forEachOrdered(disjoinings::add);
		return disjoinings;
	}

Changing this to owner in line 7 fixes the bug.