message: API: Sanitize Course chatRooms in exportJSON
  Also move 'media' deletion to "custom properties" section.
diff: @@ -172,7 +172,6 @@ courseSchema.methods.exportJSON = async function (sanitize: boolean = true, only
  delete obj.createdAt;
  delete obj.__v;
  delete obj.updatedAt;
  - delete obj.media;
  // custom properties
  if (sanitize) {
  @@ -182,6 +181,8 @@ courseSchema.methods.exportJSON = async function (sanitize: boolean = true, only
  delete obj.students;
  delete obj.courseAdmin;
  delete obj.teachers;
  + delete obj.media;
  + delete obj.chatRooms;
  }
  if (onlyBasicData) {
  