docs: public String toCsv() {
      StringBuilder sb = new StringBuilder();
      Iterator<Outcome> iter = outcomeIterator();
      while (iter.hasNext()) {
        Outcome outcome = iter.next();
        sb.append(outcome.toCsv());
        if (iter.hasNext()) {
          sb.append("\n");
        }
      }
      return sb.toString();
    }