Bug 81877 Package explorer forgets active working set [package explorer]
3.1 M4 1. open pkg explorer. 2. select a working set, pkg explorer updates and filters out projects. 3. close pkg explorer. 4. open package explorer again and the working set is no longer applied. This used to work.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/packageview/PackageExplorerPart.java
IJavaElement element= JavaCore.create((IContainer)input);
				if (element != null && element.exists())
					return element;
				return input;
			}
			
			
			
			return JavaCore.create(JavaPlugin.getWorkspace().getRoot());
		}
	}
	
	/**
	 * Answer the property defined by key.
	 */
	public Object getAdapter(Class key) {
		if (key.equals(ISelectionProvider.class))
			return fViewer;
		if (key == IShowInSource.class) {
			return getShowInSource();
		}
		if (key == IShowInTargetList.class) {
			return new IShowInTargetList() {
				public String[] getShowInTargetIds() {
					return new String[] { IPageLayout.ID_RES_NAV };
				}
			};
		}
		if (key == IContextProvider.class) {
			return JavaUIHelp.getHelpContextProvider(this, IJavaHelpContextIds.PACKAGES_VIEW);