@Override
    @Nullable
    public ChangesBunch next() {
      try {
        final int size;
        if (myOffset < bunchSize) {
          size = (int) myOffset;
          myOffset = 0;
        } else {
          myOffset -= bunchSize;
          size = bunchSize;
        }
        return new ChangesBunch(readChangesInterval(myOffset, size), true);
      }
      catch (IOException e) {
        LOG.error(e);
        return null;
      }
    }
@Override
    @Nullable
    public ChangesBunch next()