public function build()
    {
        if (!empty($this->build)) {
            return $this->build;
        }
        //root
        $this->build = [[
            'active' => true,
            'name' => '',
            'label' => '',
            'id' => 'root',
            'level' => 0,
            'uri' => '',
            'children' => []
        ]];
        foreach ($this->_data as $element) {
            $this->build[0]['children'][$element->getId()] = $element->build();
        }
        //usuwanie konfiguracji po zbudowaniu
        $this->_data = [];
        return $this->build;
    }