@Test
public void jsonSerializationWorksAsExpected() {

    final String expectedJson = "{\"" + FLUX_CAPACITOR_ID + "\":" + FLUX_CAPACITOR.toJsonString() + "}";
    final Features underTest = ImmutableFeatures.of(FLUX_CAPACITOR);
    assertThat(underTest.toJsonString()).isEqualTo(expectedJson);
}