public T getDefaultValue() {
        return defaultValue;
    }
@Test
    public void willAllowNullDefaultsForAClassProperty() {

        final SystemProperty<Class> classProperty = SystemProperty.Builder.ofType(Class.class)
            .setKey("a-null-class-property")
            .setBaseClass(AuthProvider.class)
            .setDynamic(false)
            .build();

        assertThat(classProperty.getDefaultValue(), is(nullValue()));
    }