这段代码（使用Google PHP API Client https://github.com/googleapis/google-api-php-client）回答“No upcoming events found."，显然没有检索事件，因为日历中至少有一个未来事件。
index.php

require_once __DIR__.'/vendor/autoload.php';

session_start();

putenv('GOOGLE_APPLICATION_CREDENTIALS=XXX.json');

$client = new Google\Client();
$client->useApplicationDefaultCredentials();
$client->addScope('https://www.googleapis.com/auth/calendar.events.readonly');

$calendarId = 'primary';
  $optParams = array(
    'maxResults' => 10,
    'orderBy' => 'startTime',
    'singleEvents' => TRUE,
    'timeMin' => date('c'),
  );
  
  $service = new Google_Service_Calendar($client);
  $results = $service->events->listEvents($calendarId, $optParams);

  if (count($results->getItems()) == 0) {
    print "No upcoming events found.\n";
  } else {
    print "Upcoming events:\n";
    foreach ($results->getItems() as $event) {
      $start = $event->start->dateTime;
      if (empty($start)) {
        $start = $event->start->date;
      }
      printf("%s (%s)\n", $event->getSummary(), $start);
    }
  }

我将我的www.example.com添加XXX@XXX.iam.gserviceaccount.com到可以访问我的日历事件详细信息的人员列表中，但没有任何变化。我仍在尝试检索Google日历事件列表，而不需要OAuth（服务帐户服务器到服务器）。