slice(offset, len) calls subbuffer which is not implemented

 /**
   * Given BUFFER, return a new subBuffer. Used by {@link #slice}.
   */
  protected ByteBuffer subBuffer (ByteBuffer buffer, long lowerExtreem,
                                  long upperExtreem)
  { 
    throw new RuntimeException("not implemented");
  } 
  
  public ByteBuffer slice (long off, long len)
  {
    ByteBuffer newSlice = subBuffer(this, lowWater + off, lowWater + off + len);
    newSlice.order(order());
    newSlice.wordSize(wordSize());
    return newSlice;
  }