code: @Override
    public IVersionRange invert() {
      IVersionRange irange1 = range1.invert();
      IVersionRange irange2 = range2.invert();
      return new OrRange(irange1, irange2);
    }
docs: /*
  (non-Javadoc)
  @see net.ossindex.version.impl.AbstractCommonRange#invert()