code: public final void validate() throws ValidationException {
          if (CompatibilityHints.isHintEnabled(CompatibilityHints.KEY_RELAXED_VALIDATION)) {
              if (!GREGORIAN.getValue().equalsIgnoreCase(value)) {
                  throw new ValidationException("Invalid value [" + value + "]");
              }
          } else {
              if (!GREGORIAN.getValue().equals(value)) {
                  throw new ValidationException("Invalid value [" + value + "]");
              }
          }
      }
docs: {@inheritDoc}