Bug 31374 Package Explorer does not show children of linked directories
org.eclipse.jdt.ui/ui/org/eclipse/jdt/ui/StandardJavaElementContentProvider.java
protected Object skipProjectPackageFragmentRoot(IPackageFragmentRoot root) {
		try {
			if (isProjectPackageFragmentRoot(root))
				return root.getParent(); 
			return root;
		} catch(JavaModelException e) {
			return root;
		}
	}
	
	/**
	 * Note: This method is for internal use only. Clients should not call this method.
	 */
	protected boolean isPackageFragmentEmpty(IJavaElement element) throws JavaModelException {
		if (element instanceof IPackageFragment) {
			IPackageFragment fragment= (IPackageFragment)element;
			if (!(fragment.hasChildren() || fragment.getNonJavaResources().length > 0) && fragment.hasSubpackages()) 
				return true;
		}
		return false;
	}
	/**
	 * Note: This method is for internal use only. Clients should not call this method.
	 */
	protected boolean isProjectPackageFragmentRoot(IPackageFragmentRoot root) throws JavaModelException {
		IResource resource= root.getResource();
		return (resource instanceof IProject);
	}
	
	/**