Bug 97167 wrong proposals for linked folder in New Java Project>Link Additional Resource
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/wizards/buildpaths/newsourcepage/LinkFolderDialog.java
setChanged();
            notifyObservers();
        }
    }
    
    /**
     * Validate this page and show appropriate warnings and error NewWizardMessages.
     */
    private final class Validator implements Observer {
        public void update(Observable o, Object arg) {
            String name= fFolderNameField.getText();
            IStatus nameStatus= validateFolderName(name);
            if (nameStatus.matches(IStatus.ERROR)) {
            	updateStatus(nameStatus);
            } else {
	            IStatus dependencyStatus= validateLinkLocation(name);
	            updateStatus(StatusUtil.getMoreSevere(nameStatus, dependencyStatus));
            }
        }
        
        /**
		 * Validates this page's controls.
		 *
		 * @return IStatus indicating the validation result. IStatus.OK if the 
		 *  specified link target is valid given the linkHandle.
		 */
		private IStatus validateLinkLocation(String name) {
			IWorkspace workspace= JavaPlugin.getWorkspace();
			IPath path= Path.fromOSString(fDependenciesGroup.getLinkTarget());
			IStatus locationStatus= workspace.validateLinkLocation(fContainer.getFolder(new Path(name)), path);