ProtocolVersionCacheContext.php

<?php

namespace Drupal\Core\Cache\Context;

use Drupal\Core\Cache\CacheableMetadata;

/**
 * Defines the ProtocolVersionCacheContext service, for "per protocol" caching.
 *
 * Useful to differentiate between HTTP/1.1 and HTTP/2.0 responses for example,
 * to allow responses to be optimized for protocol-specific characteristics.
 *
 * Cache context ID: 'protocol_version'.
 */
class ProtocolVersionCacheContext extends RequestStackCacheContextBase implements CacheContextInterface {
    
    /**
     * {@inheritdoc}
     */
    public static function getLabel() {
        return t('Protocol version');
    }
    
    /**
     * {@inheritdoc}
     */
    public function getContext() {
        return $this->requestStack
            ->getCurrentRequest()
            ->getProtocolVersion();
    }
    
    /**
     * {@inheritdoc}
     */
    public function getCacheableMetadata() {
        return new CacheableMetadata();
    }

}