static RoutableFactory createDocumentListReplyFactory() {
        return ProtobufCodecBuilder
                .of(VisitorReply.class, DocapiVisiting.DocumentListResponse.class)
                .encoder((apiReply) -> DocapiVisiting.DocumentListResponse.newBuilder().build())
                .decoder(DocapiVisiting.DocumentListResponse.parser(),
                        (protoReply) -> new VisitorReply(DocumentProtocol.REPLY_DOCUMENTLIST))
                .build();
    }
Implementation of MessageBus message request/response serialization built around Protocol Buffers.
documentapi/src/main/java/com/yahoo/documentapi/messagebus/protocol/RoutableFactories80.java