Inconsistent Query Explorer state after closing UML graphical editor

[abelhegedus]

When loading an UML model from the graphical Papyrus editor and loading some queries that match on UML models, the Query Explorer sometimes fails to remove the entry for the model when the editor is closed.

This was reported as part of #337

I have reproduced this with the newest version of Papyrus, UML and EIQ on the UML example from the EIQ-examples repository.

The matchers under the entry sometimes show "No matches" after closing and sometimes there are even some matches remaining (but not all).

In the background, EIQ-BASE and EIQ are putting exceptions in the error log:

EMF-IncQuery encountered an error in processing the EMF model. This happened while trying to remove the object: org.eclipse.uml2.uml.internal.impl.ClassImpl@4998cf28 (name: E, visibility: <unset>) (isLeaf: false, isAbstract: false, isFinalSpecialization: false) (isActive: false)
Stack trace: java.lang.NullPointerException

and

EMF-IncQuery Base encountered an error while traversing the EMF model to gather new information. 
java.lang.NullPointerException

[okrosa]

I can reproduce the error deterministically with the model.di file. (I only tried the model.uml according to the #337 ticket.) I try to look into it, but it is a bit hard, as the rete is blurting out 100+ error.

[abelhegedus]

I think the number of errors is of no relevance, the important part is to make sure that the user interface is cleared before throwing out the engine. Or altenratively make sure that exceptions thrown during engine disposal don't affect the Query Explorer entry removal.

[okrosa]

http://www.quickmeme.com/meme/3rkfbk/ :-)

[okrosa]

Problem solved, the GMFEditorPartListener needed to be extended so Papyrus models can be unloaded properly. This error is actually connected to the #318 issue, where we needed a similar change for loading as well.

[istvanrath]

@okrosa please cherrypick this into the maintenance branch

[okrosa]

Cherry pick completed.