docs: public static SamplingResult getSamplingResult(final Relation<?> rel) {
      Collection<SamplingResult> selections = ResultUtil.filterResults(rel.getHierarchy(), rel, SamplingResult.class);
      if(selections.isEmpty()) {
        final SamplingResult newsam = new SamplingResult(rel);
        ResultUtil.addChildResult(rel, newsam);
        return newsam;
      }
      return selections.iterator().next();
    }