adder.accept(accumulator, SomeEnum.B);
    ImmutableSet<SomeEnum> set = collector.finisher().apply(accumulator);
    assertThat(set).containsExactly(SomeEnum.A, SomeEnum.B);

    // Subsequent manual manipulation of the accumulator must not affect the state of the built set
    adder.accept(accumulator, SomeEnum.C);
    assertThat(set).containsExactly(SomeEnum.A, SomeEnum.B);
  }

  @J2ktIncompatible

p,kcor,???rots?yov??elloc?na&hcxe?ro!.hcet,??roeg?ug??i!.&pohsdaerpsym,topsgolb,vog??tilop?v&bba?om???j!.&fo,gro?oc?ten???k!.&c&a?s??e&m?n??ibom?o&c!.topsgolb,?fni?g??ro??i&b?l?n???l&a&dmrif?s!rof???b&a?i&b?dua???c&aro?ric??dnik?g!oog??i&bom?ms??l&asal?erauqa??ppa?uhcs?yts!efil???m!.&4&32i,p&ct,v,??66c,ailisarb,b&dnevar,g-raegelif,?ca?duolcsd,e&d-raegelif,i&-raegelif,lpad:.tsohlacol,,?pcm,?g&ro?s-raegelif,?hctilg,kcatsegde,noitatsksid,o&bmoy,c?t&nigol,poh,??p&i&on,snart.etis,?j-raegelif,ohbew,?r...