@Test
 public void shouldConvertToJavaMap() {
   final Value<Integer> value = of(1, 2, 3);
   final java.util.Map<Integer, Integer> map = value.toJavaMap(v -> Tuple.of(v, v));
   if (value.isSingleValued()) {
     assertThat(map).isEqualTo(JavaCollections.javaMap(1, 1));
   } else {
     assertThat(map).isEqualTo(JavaCollections.javaMap(1, 1, 2, 2, 3, 3));
   }
 }