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[Edapt] Adding a new EPackage cause NPE during Migration [message #1852386]

Fri, 13 May 2022 08:00

Eclipse User

Hi everyone,

we have a EMF/GMF/Edapt project with a long history.
There are already three separate ecore packages all tracked by one edapt history file.

Now we wanted to add a new ecore package but when edapt runs into the migration step "EPackage {foo} has been created" the migration fails with a NullPointerException:

Caused by: java.lang.NullPointerException: null
	at org.eclipse.emf.edapt.history.reconstruction.EcoreReconstructorSwitchBase.add(EcoreReconstructorSwitchBase.java:49)
	at org.eclipse.emf.edapt.history.reconstruction.EcoreReconstructorSwitchBase.create(EcoreReconstructorSwitchBase.java:95)
	at org.eclipse.emf.edapt.internal.migration.execution.internal.MigrationReconstructor$MigrationReconstructorSwitch.caseCreate(MigrationReconstructor.java:388)

When debugging you can see that the MigrationConstructor wants to create the package but the EContainer and the reference are null. Basically the new EPackage is dangling in the air and can't be created.

Is adding a new package possible? And if so, what do we have to do to resolve the NPE?

Thanks in advance :-)

Re: [Edapt] Adding a new EPackage cause NPE during Migration [message #1862358 is a reply to message #1852386]

Tue, 28 November 2023 06:34

Eclipse User

I am having the same issue when initially creating the history.

The first entry of the CompositeChange is:
EPackage {B} has been created

Same as with the EPackage that was created before, which worked.

But then when migrating the element of the Change(CreateImpl) is an EObject instead of an EPackage and i get a similar NPE

How did you solve it?

*EDIT* FUrther analysis showed that:

@Override
	public EObject getElement() {
		if (element != null && element.eIsProxy()) {
			final InternalEObject oldElement = (InternalEObject) element;
			element = eResolveProxy(oldElement);
			if (element != oldElement) {
				if (eNotificationRequired()) {
					eNotify(new ENotificationImpl(this, Notification.RESOLVE, HistoryPackage.NON_DELETE__ELEMENT,
						oldElement, element));
				}
			}
		}
		return element;
	}

the function eResolveProxy puts the EPackage correctly for A but an Proxy EObject for B. No idea why.

[Updated on: Tue, 28 November 2023 11:08] by Moderator

Re: [Edapt] Adding a new EPackage cause NPE during Migration [message #1862375 is a reply to message #1862358]

Wed, 29 November 2023 07:27

Eclipse User

The problem i had is that plugin A was wrongly named in the manifest.
Note that i have the ecore located under A.model/a.ecore

The Bundle-SymbolicName was A.model instead of plain A.
(of course i had to rename all the references to the plugin after that)

Weirdly enough this made no problem at all elswhere

Changing Bundle-SymbolicName:a;singleton:=true fixed it for me.

Hope this may be of help to someone in the future ;)

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