@Override
  protected @NotNull ProjectAbstractTreeStructureBase createStructure() {
    return new ProjectTreeStructure(myProject, ID){
      @Override
      protected AbstractTreeNode createRoot(final @NotNull Project project, @NotNull ViewSettings settings) {
        return new PackageViewProjectNode(project, settings);
      }

      @Override
      public boolean isToBuildChildrenInBackground(@NotNull Object element) {
        return Registry.is("ide.projectView.PackageViewTreeStructure.BuildChildrenInBackground");
      }
    };
  }
@Override
  protected @NotNull ProjectAbstractTreeStructureBase createStructure()