### Question:
KeyValue implements Serializable, Iterable<Object> { @Override public String toString() { return values.stream() .map(value -> ": " + Json.toJsonValue(value, true, "{ ", " }")) .collect(Collectors.joining(", ", "{ ", " }")); } KeyValue(Object... values);  KeyValue(Collection<?> values); int size(); Object get(int index); @Override Iterator<Object> iterator(); @Override boolean equals(Object o); @Override int hashCode(); @Override String toString(); Stream<Object> stream(); KeyValue normalized();  }### Answer:
@Test void testToString() throws Exception { assertThat(new KeyValue(1, 2)).hasToString("{ : 1, : 2 }"); }