assertNotNull(ArbitraryInstances.get(Object.class));
    assertEquals(0, ArbitraryInstances.get(Number.class));
    assertEquals(Charsets.UTF_8, ArbitraryInstances.get(Charset.class));
    assertEquals(Optional.empty(), ArbitraryInstances.get(Optional.class));
    assertEquals(OptionalInt.empty(), ArbitraryInstances.get(OptionalInt.class));
    assertEquals(OptionalLong.empty(), ArbitraryInstances.get(OptionalLong.class));

    assertNotNull(ArbitraryInstances.get(Joiner.class).join(ImmutableList.of("a")));
    assertNotNull(ArbitraryInstances.get(Splitter.class).split("a,b"));
    assertThat(ArbitraryInstances.get(com.google.common.base.Optional.class)).isAbsent();
    ArbitraryInstances.get(Stopwatch.class).start();
    assertNotNull(ArbitraryInstances.get(Ticker.class));
    assertFreshInstanceReturned(Random.class);
    assertEquals(