class BoundedReadFromUnboundedSource extends PTransform<PBegin, PCollection<T>> {

  public BoundedReadFromUnboundedSource<T> withMaxNumRecords(long maxNumRecords) {
    return new BoundedReadFromUnboundedSource<>(source, maxNumRecords, maxReadTime);
  }

    BoundedReadFromUnboundedSource(
      UnboundedSource<T, ?> source, long maxNumRecords, @Nullable Duration maxReadTime);

}