@Test
public void testHashCodeAndEquals() {

    final ImmutableJsonObjectNull green = ImmutableJsonObjectNull.getInstance();
    final ImmutableJsonObjectNull blue = ImmutableJsonObjectNull.getInstance();
    assertThat(green).isEqualTo(green);
    assertThat(green).isEqualTo(blue);
    assertThat(blue).isEqualTo(ImmutableJsonArrayNull.getInstance());
}