public function setPropertyType($propertyType)
    {
        if ($propertyType instanceof PropertyType) {
            $this->propertyType = $propertyType;
        } elseif (is_array($propertyType)) {
            $this->propertyType = new PropertyType($propertyType);
        } else {
            $this->propertyType = null;
            trigger_error('Argument must be an object of class PropertyType. Data loss!', E_USER_WARNING);
        }

        return $this;
    }