@ValueSource(strings = { "none", "No_Retry", "retain_payload", "UNKNOWN", "NO-RETRY" })
    @DisplayName("valueOf with unknown or differently-cased names throws IllegalArgumentException")
    void valueOfRejectsUnknownOrCaseMismatch(String badName) {
        IllegalArgumentException ex = assertThrows(IllegalArgumentException.class, () -> RequestParam.valueOf(badName));