Your definition is quite right but it is just missing the @DynamicLabels annotation on your nodeLabels field. With this you can manage additional labels for your entity.
I have another question : i use another relational database in the same project and i read that it is not recomanded to use impeartive with reactive programing in the same project.
Do you think that i can use the rx library in this case ?
You can use it, there is no technical limitation in general.
But doing imperative operations during a reactive one is an anti-pattern.
Say you want to persist data through the reactive SDN-RX layer but the very same service method interacts also with the blocking relational database.
Just as a reminder: SDN-RX does also support imperative programming and you do not have to use the reactive parts of the framework. We develop both programming models in parallel, with a few limitations of course if one feature does not make sense in the reactive world or vice-versa.