How to use

NonEssentialEmptyLibraryContainerFilter

in

org.eclipse.jdt.internal.ui.navigator

  @Override
  protected boolean doSelect(Viewer viewer, Object parent, Object element) {
    if (element instanceof PackageFragmentRootContainer) {
      if (isApplicable() && viewer instanceof StructuredViewer) {
        PackageFragmentRootContainer rootContainer= (PackageFragmentRootContainer) element;
        return rootContainer.getChildren().length > 0 ? hasFilteredChildren((StructuredViewer) viewer, rootContainer) : false;
      }
    }
    return true;
  }
}

  @Override
  protected boolean doSelect(Viewer viewer, Object parent, Object element) {
    if (element instanceof PackageFragmentRootContainer) {
      if (isApplicable() && viewer instanceof StructuredViewer) {
        PackageFragmentRootContainer rootContainer= (PackageFragmentRootContainer) element;
        return rootContainer.getChildren().length > 0 ? hasFilteredChildren((StructuredViewer) viewer, rootContainer) : false;
      }
    }
    return true;
  }
}