docs: public Optional<String> selectByKey(DbSession dbSession, String key) {
      checkKey(key);
  
      InternalPropertiesMapper mapper = getMapper(dbSession);
      InternalPropertyDto res = enforceSingleElement(key, mapper.selectAsText(singletonList(key)));
      if (res == null) {
        return Optional.empty();
      }
      if (res.isEmpty()) {
        return OPTIONAL_OF_EMPTY_STRING;
      }
      if (res.getValue() != null) {
        return Optional.of(res.getValue());
      }
      res = enforceSingleElement(key, mapper.selectAsClob(singletonList(key)));
      if (res == null) {
        Loggers.get(InternalPropertiesDao.class)
          .debug("Internal property {} has been found in db but has neither text value nor is empty. " +
            "Still it couldn't be retrieved with clob value. Ignoring the property.", key);
        return Optional.empty();
      }
      return Optional.of(res.getValue());
    }