public function getProperty($systemName)
    {
        foreach ($this->propertySets as $propertySet) {
            /** @var PropertySet $propertySet */
            foreach ($propertySet->getProperties() as $property) {
                if ($property->getPropertyType()->getSystemName() == $systemName) {
                    return $property;
                }
            }
        }
        throw new PropertyNotFoundException('No Property with the system name "' . $systemName . '" exists.');
    }