Bug 120544 [build path] Editing external source folder does not persist
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/wizards/buildpaths/SourceContainerWorkbookPage.java
CPListElement newElement= new CPListElement(fCurrJProject, IClasspathEntry.CPE_SOURCE);
				AddSourceFolderWizard wizard= newSourceFolderWizard(newElement, fFoldersList.getElements(), fOutputLocationField.getText());
				OpenBuildPathWizardAction action= new OpenBuildPathWizardAction(wizard);
				action.run();
			} else if (index == IDX_ADD_LINK) {
				List elementsToAdd= new ArrayList(10);
				CPListElement entry= openNewLinkedSourceContainerDialog(null);
				if (entry != null) {
					elementsToAdd.add(entry);
				}
				if (!elementsToAdd.isEmpty()) {
					if (fFoldersList.getSize() == 1) {
						CPListElement existing= (CPListElement) fFoldersList.getElement(0);
						if (existing.getResource() instanceof IProject) {
							askForChangingBuildPathDialog(existing);
						}
					}
					HashSet modifiedElements= new HashSet();
					askForAddingExclusionPatternsDialog(elementsToAdd, modifiedElements);
					
					fFoldersList.addElements(elementsToAdd);
					fFoldersList.postSetSelection(new StructuredSelection(elementsToAdd));
					
					if (!modifiedElements.isEmpty()) {
						for (Iterator iter= modifiedElements.iterator(); iter.hasNext();) {
							Object elem= iter.next();
							fFoldersList.refresh(elem);
							fFoldersList.expandElement(elem, 3);
						}
					}