prepareUnmodifiableTests(HashMultimap.<String, Integer>create(), false, null, null);
    SerializableTester.reserializeAndAssert(unmodifiable);
  }

  @GwtIncompatible // slow (~10s)
  public void testUnmodifiableTreeMultimap() {
    checkUnmodifiableMultimap(TreeMultimap.<String, Integer>create(), false, "null", 42);
  }

  @J2ktIncompatible
  @GwtIncompatible // SerializableTester