<?php
/**
 * @file
 * Contains \Drupal\example_module\Controller\ExampleModuleController.
 */
 
// THIS FILE BELONGS AT /example_module/src/Controller/ExampleModuleController.php

namespace Drupal\example_module\Controller;

use Drupal\Core\Controller\ControllerBase;

/**
 * An example controller.
 */
class ExampleModuleController extends ControllerBase {

  /**
   * {@inheritdoc}
   */
  public function content() {
    $build = array(
      '#type' => 'markup',
      '#markup' => t('Hello World!'),
    );
    return $build;
  }
}