LinkGenerationTestHooks.php

<?php

declare (strict_types=1);
namespace Drupal\link_generation_test\Hook;

use Drupal\Core\Hook\Attribute\Hook;

/**
 * Hook implementations for link_generation_test.
 */
class LinkGenerationTestHooks {
    
    /**
     * Implements hook_link_alter().
     */
    public function linkAlter(&$variables) {
        if (\Drupal::state()->get('link_generation_test_link_alter', FALSE)) {
            // Add a text to the end of links.
            if (\Drupal::state()->get('link_generation_test_link_alter_safe', FALSE)) {
                $variables['text'] = t('@text <strong>Test!</strong>', [
                    '@text' => $variables['text'],
                ]);
            }
            else {
                $variables['text'] .= ' <strong>Test!</strong>';
            }
        }
    }

}