code: public @NotNull <T> Optional<T> findOptional(@NotNull Class<T> cl, @NotNull SqlQuery query) {
          return executeQuery(rowMapperForClass(cl).optional(), query);
      }
docs: Finds a unique result from database, converting the database row to given class using default mechanisms.
  Returns empty if there are no results or if single null result is returned.
  
  @throws NonUniqueResultException if there are multiple result rows