assertThrows(IllegalStateException.class, builder1::weakValues);
    assertThrows(IllegalStateException.class, builder1::softValues);

    CacheBuilder<Object, Object> builder2 = CacheBuilder.newBuilder().softValues();
    assertThrows(IllegalStateException.class, builder2::softValues);
    assertThrows(IllegalStateException.class, builder2::weakValues);
  }

  @J2ktIncompatible
  @GwtIncompatible // Duration