@Override
 public void resetBuffer() {
   checkNotCommitted();
   outputStream.resetBuffer();
 }
 @Override
 public int getBufferSize() {
   return outputStream.getBufferSize();
 }
 @Override
 public void flushBuffer() throws IOException {
   checkNotCommitted();
   outputStream.flush();
 }
 @Override
 public void setBufferSize(int size) {
   checkNotCommitted();
   outputStream.setBufferSize(size);
 }