private static DocapiVisiting.VisitorParameter toProtoVisitorParameter(String key, byte[] value) {
        return DocapiVisiting.VisitorParameter.newBuilder()
                .setKey(key)
                .setValue(ByteString.copyFrom(value))
                .build();
    }
Implementation of MessageBus message request/response serialization built around Protocol Buffers.
documentapi/src/main/java/com/yahoo/documentapi/messagebus/protocol/RoutableFactories80.java