public static HedgeConfig ofDefaults() {
        return new Builder().build();
    }
@Test
    public void builderTimeoutIsNull() {
        exception.expect(NullPointerException.class);
        exception.expectMessage(HEDGE_DURATION_MUST_NOT_BE_NULL);

        HedgeConfig.Builder.fromConfig(HedgeConfig.ofDefaults())
            .preconfiguredDuration(null);
    }