As explained on the Client Spring page, the GraphQL plugin defines an auto-configuration class, that provides default Spring beans. And the whole system is built as a Spring Boot app.
So, you can personalize the plugin behavior by:
If you don't use the Spring app, you can use a preconfigured Jersey client instance to support customization of the rest request:
public QueryTypeExecutor(String graphqlEndpoint, Client client, ObjectMapper objectMapper)
The plugin generates the code, from a Velocity templates. You can override the provided templates.
Please take a look at the custom templates doc for all the details.