class ImmutableConfig

class ImmutableConfig extends Config {
    
    /**
     * {@inheritdoc}
     */
    public function set($key, $value) {
        throw new ImmutableConfigException("Can not set values on immutable configuration {$this->getName()}:{$key}. Use \\Drupal\\Core\\Config\\ConfigFactoryInterface::getEditable() to retrieve a mutable configuration object");
    }
    
    /**
     * {@inheritdoc}
     */
    public function clear($key) {
        throw new ImmutableConfigException("Can not clear {$key} key in immutable configuration {$this->getName()}. Use \\Drupal\\Core\\Config\\ConfigFactoryInterface::getEditable() to retrieve a mutable configuration object");
    }
    
    /**
     * {@inheritdoc}
     */
    public function save($has_trusted_data = FALSE) {
        throw new ImmutableConfigException("Can not save immutable configuration {$this->getName()}. Use \\Drupal\\Core\\Config\\ConfigFactoryInterface::getEditable() to retrieve a mutable configuration object");
    }
    
    /**
     * Deletes the configuration object.
     *
     * @return \Drupal\Core\Config\Config
     *   The configuration object.
     */
    public function delete() {
        throw new ImmutableConfigException("Can not delete immutable configuration {$this->getName()}. Use \\Drupal\\Core\\Config\\ConfigFactoryInterface::getEditable() to retrieve a mutable configuration object");
    }

}