protected function initializeClassValue()
    {
        $classesConfiguration = $this->formService
            ->getFormObject()
            ->getConfiguration()
            ->getRootConfiguration()
            ->getView()
            ->getClasses();

        /** @var ViewClass $class */
        $class = ObjectAccess::getProperty($classesConfiguration, $this->classNameSpace);

        if (false === $class->hasItem($this->className)) {
            throw UnregisteredConfigurationException::cssClassNameNotFound($this->arguments['name'], $this->classNameSpace, $this->className);
        }

        $this->classValue = $class->getItem($this->className);
    }