code: @Override
    public IVersionRange invert() {
      switch (operator) {
        case ">":
          return new VersionRange("<=", version);
        case ">=":
          return new VersionRange("<", version);
        case "<":
          return new VersionRange(">=", version);
        case "<=":
          return new VersionRange(">", version);
        default:
          throw new UnsupportedOperationException();
      }
    }
docs: /*
  (non-Javadoc)
  @see net.ossindex.version.impl.AbstractCommonRange#invert()