code: public ArrayList<FileSlice> mapBlock(int piece, long offset, int size) {
          return FileStorage.mapBlock(ti.map_block(piece, offset, size));
      }
docs: This function will map a piece index, a byte offset within that piece and
  a size (in bytes) into the corresponding files with offsets where that data
  for that piece is supposed to be stored.
  
  @param piece
  @param offset
  @param size
  @return
  @see com.frostwire.jlibtorrent.FileSlice