code: static int getPortableArrayCellPosition(BufferObjectDataInput in, int streamPosition, int cellIndex)
              throws IOException {
          return in.readInt(streamPosition + cellIndex * Bits.INT_SIZE_IN_BYTES);
      }
docs: Calculates and reads the position of the Portable object stored in a Portable array under the given index.
  
  @param in             data input stream
  @param streamPosition streamPosition to begin the reading from
  @param cellIndex      index of the cell
  @return the position of the given portable object in the stream
  @throws IOException on any stream errors