code: public BoxRequestsMetadata.GetFileMetadata getMetadataRequest(String id) {
          BoxRequestsMetadata.GetFileMetadata request = new BoxRequestsMetadata.GetFileMetadata(getFileMetadataUrl(id), mSession);
          return request;
      }
docs: Gets a request that retrieves all the metadata on a file
  
  @param id    id of the file to retrieve metadata for
  @return  request to retrieve metadata on a file