Bug 81426 Package Explorer shows nothing after drill into working set, then show projects
I200412160800 - switch Package Explorer to working sets - context menu > Go Into a working set - Show > Projects -> view is empty -> view toolbar button 'Up to Working Sets' does not do anything
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);