code: public PeerRequest mapFile(int file, long offset, int size) {
          return new PeerRequest(fs.map_file(file, offset, size));
      }
docs: Returns a {@link com.frostwire.jlibtorrent.PeerRequest} representing the
  piece index, byte offset and size the specified file range overlaps.
  This is the inverse mapping of {@link #mapBlock(int, long, int)}.
  <p>
  Note that the {@link PeerRequest} return type
  is meant to hold bittorrent block requests, which may not be larger
  than 16 kiB. Mapping a range larger than that may return an overflown
  integer.
  
  @param file
  @param offset
  @param size
  @return