title: Google Classroom API modifyAttachments
body: <p>When executing the <code>courses.courseWork.studentSubmissions.modifyAttachments</code> method in the Google Classroom API, a 403 error is returned when I try to add the attachment to the student's submission.</p>
  
  <pre><code>GoogleJsonResponseException:  
  {
    "code" : 403,
    "errors" : [ {
      "domain" : "global",
      "message" : "@ProjectPermissionDenied The Developer Console project is not permitted to make this request.",
      "reason" : "forbidden"
    } ],
    "message" : "@ProjectPermissionDenied The Developer Console project is not permitted to make this request.",
    "status" : "PERMISSION_DENIED"
  }
  </code></pre>
  
  <p>The call is being made from an authenticated student account and being added as a Link resource.  The Developer Console project DOES have the Google Classroom API enabled, and other calls to the Google Classroom API are working fine, such as <code>courses.list</code> and <code>courses.courseWork.studentSubmissions.get</code>.  What am I missing?  The same error is returned when using the <a href="https://developers.google.com/classroom/reference/rest/v1/courses.courseWork.studentSubmissions/modifyAttachments#try-it" rel="nofollow">Try it!</a> app in the Google Classroom documentation site.   </p>