@Test
public void toStringTest() {

    CombinedSchema subject = CombinedSchema
            .allOf(asList(BooleanSchema.INSTANCE, NullSchema.INSTANCE))
            .description("descr")
            .build();
    JSONObject actual = new JSONObject(subject.toString());
    assertThat(actual, sameJsonAs(new JSONObject("{\"allOf\":["
            + BooleanSchema.INSTANCE.toString()
            + ", "
            + NullSchema.INSTANCE
            + "], \"description\":\"descr\"}")));
}