code: public BoxRequestsFile.FilePreviewed getFilePreviewedRequest(String fileId) {
          return new BoxRequestsFile.FilePreviewed(fileId, getPreviewFileUrl(), mSession);
      }
docs: Gets a request that inform the server that a file was previewed.
  This makes the file to be included on the recents list.
  
  @param  fileId
  @return request to inform the server that a file was previewed