code: public boolean getBoolean(String key) {
      String value = getString(key);
      return StringUtils.isNotEmpty(value) && Boolean.parseBoolean(value);
    }
docs: Effective value as boolean. It is {@code false} if {@link #getString(String)}
  does not return {@code "true"}, even if it's not a boolean representation.
  @return {@code true} if the effective value is {@code "true"}, else {@code false}.