Bug 329310 Part service does not autogenerate stacks if the last container is not one
tests/org.eclipse.e4.ui.tests/src/org/eclipse/e4/ui/tests/application/EPartServiceTest.java
MPartDescriptor partDescriptor = org.eclipse.e4.ui.model.application.descriptor.basic.impl.BasicFactoryImpl.eINSTANCE
				.createPartDescriptor();
		partDescriptor.setElementId("partId"); 
		application.getDescriptors().add(partDescriptor);
		MPart part = BasicFactoryImpl.eINSTANCE.createPart();
		part.setElementId("partId"); 
		window.getSharedElements().add(part);
		MPerspectiveStack perspectiveStack = AdvancedFactoryImpl.eINSTANCE
				.createPerspectiveStack();
		window.getChildren().add(perspectiveStack);
		window.setSelectedElement(perspectiveStack);
		MPerspective perspectiveA = AdvancedFactoryImpl.eINSTANCE
				.createPerspective();
		perspectiveStack.getChildren().add(perspectiveA);
		perspectiveStack.setSelectedElement(perspectiveA);
		MPerspective perspectiveB = AdvancedFactoryImpl.eINSTANCE
				.createPerspective();
		perspectiveStack.getChildren().add(perspectiveB);
		initialize(applicationContext, application);
		getEngine().createGui(window);
		EModelService modelService = window.getContext().get(
				EModelService.class);
		EPartService partService = window.getContext().get(EPartService.class);
		partService.showPart(part, PartState.ACTIVATE);
		List<MPart> partsA = modelService.findElements(perspectiveA,
				part.getElementId(), MPart.class, null);
		assertEquals(1, partsA.size());
		assertEquals(part, partsA.get(0));
		List<MPlaceholder> placeholdersA = modelService.findElements(
				perspectiveA, part.getElementId(), MPlaceholder.class, null);