Add template parameters in EasyAdmin

AdminController.php

<?php

namespace App\Controller;

use EasyCorp\Bundle\EasyAdminBundle\Controller\AdminController as BaseAdminController;

/**
 * General controller for administrating all entities
 */
class AdminController extends BaseAdminController
{

    /**
     * Used to add/modify/remove parameters before passing them to the Twig template.
     * If the controller implements an action specific method (e.g. renderEditTemplate)
     * it will be used
     *
     * @param string $actionName The name of the current action (list, show, new, etc.)
     * @param string $templatePath The path of the Twig template to render
     * @param array $parameters The parameters passed to the template
     *
     * @return \Symfony\Component\HttpFoundation\Response
     */
    protected function renderTemplate($actionName, $templatePath, array $parameters = [])
    {
        $customRenderMethod = 'render' . ucfirst($actionName) . 'Template';

        if (method_exists($this, $customRenderMethod)) {
            return $this->$customRenderMethod($actionName, $templatePath, $parameters);
        }

        return $this->render($templatePath, $parameters);
    }

}

CustomController.php

<?php

namespace App\Controller;

use App\Controller\AdminController as BaseAdminController;

class CustomController extends BaseAdminController
{

    /**
     * Used to add/modify/remove parameters before passing them to the Twig template.
     * Instead of defining a render method per action (list, show, search, etc.) use
     * the $actionName argument to discriminate between actions.
     *
     * @param string $actionName The name of the current action (list, show, new, etc.)
     * @param string $templatePath The path of the Twig template to render
     * @param array $parameters The parameters passed to the template
     *
     * @return \Symfony\Component\HttpFoundation\Response
     */
    public function renderEditTemplate($actionName, $templatePath, array $parameters = [])
    {
        $parameters['myCustomParameter'] = 'Custom Value';

        return $this->render($templatePath, $parameters);
    }

}