Creates a ReactiveMongo BSONHandler based on the given Pickler.
Creates a ReactiveMongo document handler based on the given Pickler.
Creates a ReactiveMongo document handler based on the given Pickler.
If the pickler produces an Object, it is used directly. Otherwise, if the pickler produces a primitive value, it is wrapped in a BSONDocument that looks like { "_id" -> pickled value, "$$wrapped" -> true }.