docs: @Nonnull
    @ReturnsMutableCopy
    public static ICommonsMap <String, Boolean> getAllMenuItemIDs (@Nonnull final IMenuTree aMenuTree)
    {
      ValueEnforcer.notNull (aMenuTree, "MenuTree");
  
      final ICommonsMap <String, Boolean> ret = new CommonsHashMap <> ();
      TreeVisitor.visitTree (aMenuTree,
                             new DefaultHierarchyVisitorCallback <DefaultTreeItemWithID <String, IMenuObject>> ()
                             {
                               @Override
                               public EHierarchyVisitorReturn onItemBeforeChildren (@Nonnull final DefaultTreeItemWithID <String, IMenuObject> aItem)
                               {
                                 ret.put (aItem.getID (), Boolean.valueOf (aItem.hasChildren ()));
                                 return EHierarchyVisitorReturn.CONTINUE;
                               }
                             });
      return ret;
    }