@Override
    public double read() {
        return gaugeSource.read();
    }
@Test
    public void whenLongGaugeField() {
        SomeObject someObject = new SomeObject();
        metricsRegistry.registerStaticMetrics(someObject, "foo");

        DoubleGauge gauge = metricsRegistry.newDoubleGauge("foo.longField");
        assertEquals(someObject.longField, gauge.read(), 0.1);
    }