@Test
public void collectingFieldKeysOfObjectReturnsExpectedArray() {

    final JsonArray expectedArray = JsonFactory.newArrayBuilder() //
            .add(JsonFactory.newValue(ID_KEY.toString())) //
            .add(JsonFactory.newValue(STATE_KEY.toString())) //
            .add(JsonFactory.newValue(MANUFACTURER_KEY.toString())) //
            .build();
    final JsonArray actualArray = KNOWN_JSON_OBJECT.stream() //
            .collect(JsonCollectors.fieldKeysToArray());
    DittoJsonAssertions.assertThat(actualArray).isEqualTo(expectedArray);
}