code: public StreamVariantsRequest getStreamVariantsRequest(StreamVariantsRequest prototype) {
      return StreamVariantsRequest.newBuilder(prototype)
          .setReferenceName(referenceName)
          .setStart(start)
          .setEnd(end)
          .build();
    }
docs: Construct a StreamVariantsRequest for the Contig using a prototype using a prototype request.
  
  @param prototype A partially filled in request object.
  @return the request object