title: Google Calendar PHP API Not Sending Invite Emails
body: <p>I have successfully integrated with Google Calendar using PHP with a Service Account.</p>
  
  <p><strong>What I can do:</strong></p>
  
  <ul>
  <li>Update the calendar event.</li>
  <li>Add attendees to the calendar event.</li>
  </ul>
  
  <p><strong>What I can not do:</strong></p>
  
  <ul>
  <li>Send invite emails when new attendees are added.</li>
  </ul>
  
  <p><strong>Here is the entire code that I use to accomplish everything so far:</strong></p>
  
  <pre><code>putenv('GOOGLE_APPLICATION_CREDENTIALS=credentials.json');
  
  $client = new Google_Client();
  $client-&gt;useApplicationDefaultCredentials();
  $client-&gt;setScopes('https://www.googleapis.com/auth/calendar');
  $client-&gt;setSubject('example@gmail.com');
  
  $service = new Google_Service_Calendar($client);
  
  $calendarID = 'primary';
  $eventID = 'XXXXXXXXX';
  $event = new Google_Service_Calendar_Event(array(
      'sendNotifications' =&gt; true,
      'attendees' =&gt; array(
          array('email' =&gt; 'email1@gmail.com)
      )
  ));
  
  $event = $service-&gt;events-&gt;patch($calendarID, $eventID, $event);
  </code></pre>