Java Protobuf Any vs Oneof

animals.proto

message Dog {

}

message Cat {

}

message Elephant {

}


message AnyAnimal {
    google.protobuf.Any animal = 1;
}

message OneAnimal {
    oneof animal {
        Dog dog = 1;
        Cat cat = 2;
        Elephant elephant = 3;
    }
}

serde.java

class Serde {
  static {
           // Any Animal Serialization
        AnyAnimal anyDogAnimal = AnyAnimal.newBuilder().setAnimal(
                Any.pack(Dog.newBuilder().build())
        ).build();

        AnyAnimal anyCatAnimal = AnyAnimal.newBuilder().setAnimal(
                Any.pack(Cat.newBuilder().build())
        ).build();

        // One Animal Serialization
        OneAnimal oneAnimalDog = OneAnimal.newBuilder().setDog(Dog.newBuilder().build()).build();
        OneAnimal oneAnimalCat = OneAnimal.newBuilder().setCat(Cat.newBuilder().build()).build();

        // Any Animal Deserialization
        Any anAnimal = anyDogAnimal.getAnimal();
        GeneratedMessageV3 output1 = Stream.of(Dog.class, Cat.class, Elephant.class)
                .filter(klass -> anAnimal.is(klass))
                .map(klass -> {
                    try {
                        return anAnimal.unpack(klass);
                    } catch (InvalidProtocolBufferException e) {
                        e.printStackTrace();
                    }
                    return null;
                })
                .limit(1)
                .reduce(null, (x, y) -> y);

        if (output1 instanceof Dog) {
            // ...
        }
        else if (output1 instanceof Cat) {
            //
        }

        // One Animal deserialzation (switch)
        OneAnimal.AnimalCase animalCase = oneAnimalDog.getAnimalCase();
        switch (animalCase) {
            case DOG: return oneAnimalDog.getDog();
            case CAT: return oneAnimalDog.getCat();
            case ELEPHANT:: return oneAnimalDog.getElephant();
            case ANIMAL_NOT_SET: return null;
        }

        // One Animal serialization (by field descriptors)
        Descriptors.OneofDescriptor field = oneAnimalCat.getDescriptorForType().getOneofs().stream()
                .filter(oneofDescriptor -> oneofDescriptor.getName().equals("animal")).reduce(null, (x, y) -> y);
        Descriptors.FieldDescriptor field2 = oneAnimalCat.getOneofFieldDescriptor(field);
        Object object = oneAnimalCat.getField(field2);
        if (object instanceof Cat) {
            return (Cat) object;
        }
        else if (object instanceof Dog) {
            return (Dog) object;
        }
    }
  }