code: public function paintGroupEnd($message)
      {
          $node    = $this->_stack->pop();
          $current = $this->_stack->peek();
          if ($current) {
              if ($node->isFailed()) {
                  $current->fail();
              }
              $current->putChild($node);
          } else {
              $this->_graph = $node;
          }
          parent::paintGroupEnd($message);
      }
docs: acceptor for end of test group.
  final group pops the collected treemap nodes and assigns it to the internal graph property.