Avoid concurrent modification exception in Action service
Adding the ACC example from the file menu, the following exception has occurred.
Side condition: two larger models and one have already been in the workspace before. Note: The issue is hard to reproduce since it depends on the timing.
!ENTRY org.eclipse.ui 4 4 2021-09-08 09:15:49.923 !MESSAGE An internal error has occurred. !STACK 0 java.util.ConcurrentModificationException at java.base/java.util.AbstractList$RandomAccessSpliterator.checkAbstractListModCount(AbstractList.java:743) at java.base/java.util.AbstractList$RandomAccessSpliterator.tryAdvance(AbstractList.java:707) at java.base/java.util.stream.ReferencePipeline.forEachWithCancel(ReferencePipeline.java:127) at java.base/java.util.stream.AbstractPipeline.copyIntoWithCancel(AbstractPipeline.java:502) at java.base/java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:488) at java.base/java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:474) at java.base/java.util.stream.MatchOps$MatchOp.evaluateSequential(MatchOps.java:230) at java.base/java.util.stream.MatchOps$MatchOp.evaluateSequential(MatchOps.java:196) at java.base/java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234) at java.base/java.util.stream.ReferencePipeline.anyMatch(ReferencePipeline.java:528) at org.fortiss.tooling.kernel.ui.internal.actions.DeleteAction.computeEnabled(DeleteAction.java:210) at org.fortiss.tooling.kernel.ui.extension.base.EObjectActionBase.refresh(EObjectActionBase.java:101) at org.fortiss.tooling.kernel.ui.extension.base.EObjectActionBase.refresh(EObjectActionBase.java:141) at org.fortiss.tooling.kernel.ui.internal.ActionService.refresh(ActionService.java:196) at org.fortiss.tooling.kernel.ui.internal.views.NavigatorViewPart$1.runInUIThread(NavigatorViewPart.java:118) at org.eclipse.ui.progress.UIJob.lambda$0(UIJob.java:95) at org.eclipse.swt.widgets.RunnableLock.run(RunnableLock.java:40) at org.eclipse.swt.widgets.Synchronizer.runAsyncMessages(Synchronizer.java:185) at org.eclipse.swt.widgets.Display.runAsyncMessages(Display.java:3963) at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3590) at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$5.run(PartRenderingEngine.java:1160) at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:338) at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:1049) at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:155) at org.eclipse.ui.internal.Workbench.lambda$3(Workbench.java:660) at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:338) at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:559) at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:154) at org.fortiss.af3.rcp.application.AF3Application.start(AF3Application.java:49) at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:203) at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:137) at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:107) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:401) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:255) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.base/java.lang.reflect.Method.invoke(Method.java:566) at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:657) at org.eclipse.equinox.launcher.Main.basicRun(Main.java:594) at org.eclipse.equinox.launcher.Main.run(Main.java:1465) at org.eclipse.equinox.launcher.Main.main(Main.java:1438)