Bugfix/fix diamond problem & refactoring #1590

[dbinkele]

solves #1590

[kbirken]

PivotInfo is gone now, congrats! And finally IConfigListVarPoint had to vanish, R.I.P. :-)

Here are some findings from my code review:

• class Segment
  • On the first constructor, there is the statement this.targetNode = targetIVAA.parent;. This might be wrong, as we allow concepts from artifact DSLs to implement interface IVarAA, instead of using a NodeAttribute. Use instead IVAA.artifactRoot().
  • This class should be non-mutable, thus it should not not have a setTarget method.
  • In order to enforce this in future, all private members should be final (new).
• class AbstractSkelTreeBuilder
  • Please implement the new code in method finish() as member method public ArtifactPath asInstanceOnlyPath() in ArtifactPath
• class SkeletonNode
  • I think method getPath is deprecated long enough and should be deleted now.
  • The comment in method getUniqueLabel in the inner if-statement should be updated now as the condition has been changed.
  • The methods targetIVAA() and target should be simplified similar to this.path.segmentsAsList().findLast({it => it.getTarget().isNotNull; }).?getTarget();
  • I would prefer if method setInstance() could be avoided, as it makes the class even more mutable. But the caller seems to be in IETS3.Core...
• class SkeletonTreeGraphCreator
  • The code segments.last.getTargetIVAA().artifactName() could be replaced by using the above method SkeletonNode.getTargetIVAA().

[dbinkele]

@kbirken All review findings have been addressed. Please have look again