ProxyBuilder.php

<?php

namespace Drupal\Core\ProxyBuilder;

use Drupal\Component\ProxyBuilder\ProxyBuilder as BaseProxyBuilder;

/**
 * Extend the component proxy builder by using the DependencySerializationTrait.
 */
class ProxyBuilder extends BaseProxyBuilder {
    
    /**
     * {@inheritdoc}
     */
    protected function buildUseStatements() {
        $output = parent::buildUseStatements();
        $output .= 'use \\Drupal\\Core\\DependencyInjection\\DependencySerializationTrait;' . "\n\n";
        return $output;
    }

}