public static <T>CombinedDownloadTask<T> single(DownloadTask<T> task){
  Objects.requireNonNull(task);
  return new SingleCombinedTask<T>(task);
}

public static < T > CombinedDownloadTask < T > single ( DownloadTask < T > task ) { Objects . requireNonNull ( task ) ; return new SingleCombinedTask < T > ( task ) ; }
creates a combineddownloadtask from a downloadtask .
