public static Builder custom() {
        return new Builder();
    }
@Test
    public void shouldCreateAmountCutoff() {
        HedgeConfig config = HedgeConfig.custom()
            .averagePlusAmountDuration(200, false, 100).build();

        HedgeDurationSupplier supplier = HedgeDurationSupplier.fromConfig(config);

        then(((AverageDurationSupplier) supplier)).isInstanceOf(AverageDurationSupplier.class);
        then(((AverageDurationSupplier) supplier).getFactor()).isEqualTo(200);
        then(((AverageDurationSupplier) supplier).shouldMeasureErrors()).isFalse();
        then(((AverageDurationSupplier) supplier).shouldUseFactorAsPercentage()).isFalse();
    }