public function getEndPoints()
    {
        $endPoints = array();
        if (!$this->hasChildren()) {
            return $endPoints;
        }

        foreach ($this->_children as $child) {
            $value = $child->getValue();

            if (null === $value) {
                $endPoints[] = $this;
            } elseif ((null !== $value)
                && $child->hasChildren())
            {
                $childEndPoints = $child->getEndPoints();
                if (!empty($childEndPoints)) {
                    $endPoints = array_merge($endPoints, $childEndPoints);
                }
            } elseif ((null !== $value) && !$child->hasChildren()) {
                $endPoints[] = $child;
            }
        }

        return $endPoints;
    }