quarkus.cache.redis.value-type to protobuf values

In quarkus, I want to use the redis-based cache. The results are protobuf objects, which can be serialized to byte[] or ByteString.

I understand that the value type must be serializable, so I tried to use

quarkus.cache.redis.value-type=byte[]

Then it gives me the error, as byte[] is not a class.

I worked around by using String, but in the code, I had to firstly convert byte[] to String when storing the result into redis, and then get the byte[] from String when get it back. This is not idea.

What quarkus.cache.redis.value-type should I use in this case?