ConfigCrudEvent.php

<?php

namespace Drupal\Core\Config;

use Symfony\Component\EventDispatcher\Event;

/**
 * Wraps a configuration event for event listeners.
 */
class ConfigCrudEvent extends Event {
    
    /**
     * Configuration object.
     *
     * @var \Drupal\Core\Config\Config
     */
    protected $config;
    
    /**
     * Constructs a configuration event object.
     *
     * @param \Drupal\Core\Config\Config $config
     *   Configuration object.
     */
    public function __construct(Config $config) {
        $this->config = $config;
    }
    
    /**
     * Gets configuration object.
     *
     * @return \Drupal\Core\Config\Config
     *   The configuration object that caused the event to fire.
     */
    public function getConfig() {
        return $this->config;
    }
    
    /**
     * Checks to see if the provided configuration key's value has changed.
     *
     * @param string $key
     *   The configuration key to check if it has changed.
     *
     * @return bool
     */
    public function isChanged($key) {
        return $this->config
            ->get($key) !== $this->config
            ->getOriginal($key);
    }

}