Spring Cloud Function (GCP adapter) throws Hibernate lazy could not initialize proxy - no session - spring-boot

Question

This is a common error in Spring when tries to transform automatically an entity object whit some hibernate proxys but i dont't know how to load Jackson DataType Hibernate5 module in Spring cloud functions gcp adapter.
#SpringBootApplication
#Log4j2
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
#Bean
public WebMvcConfigurer corsConfigurer() {
log.info("configurando cors");
return new WebMvcConfigurer() {
#Override
public void addCorsMappings(CorsRegistry registry) {
registry.addMapping("/**").allowedOrigins("*");
}
};
}
#Bean
public Module datatypeHibernateModule() {
log.info("Cargando modulo hibernate jackson");
return new Hibernate5Module();
}
}
If i use the same code whit normal Spring boot project the module works but in this case i found on the log the adapter don't used Jackson and they implements Gson.
at com.google.gson.Gson.toJson(Gson.java:638)
at com.google.gson.Gson.toJson(Gson.java:618)
at org.springframework.cloud.function.json.GsonMapper.toJson(GsonMapper.java:70)
This is the entire log file
My first workaround is change the Page object for String and use manually jackson mapper.
public class ObtenerEstados implements Function<Void, String> {
#Autowired
private EstadoService estadoService;
#SneakyThrows
#Override
public String apply(Void unused) {
Page<Estado> page = estadoService.buscarTodos(0, 33);
ObjectMapper objectMapper = new ObjectMapper();
objectMapper.registerModule(new Hibernate5Module());
String objectAsString = objectMapper.writeValueAsString(page);
return objectAsString;
}
}
I created two branches on the Github repository
functions (this branch have the bug)
function-jackson-hibernate5 (this branch have the workaround)
If you haved already installed Docker and Docker Compose you can reproduce the bug easy.
Follow the next steps:
git clone https://github.com/ripper2hl/sepomex.git
cd sepomex
git checkout -b dev origin/functions
docker-compose pull db
docker-compose up -d db
export spring_profiles_active=local
mvn -Pgcp function:run
And execute with a curl or any REST client
curl http://localhost:8080/
I know the alternative for use a DTO object but i prefer not use this option

Answer 1

So whenever Gson is on the classpath it is given priority and of course with Google that is the case. Please set spring.http.converters.preferred-json-mapper=jackson property to force Jackson.

Answer 2

Finally i fixed with this fragment of code
#SpringBootApplication
public class Application {
public static void main(String[] args) {
SpringApplication.run(Application.class, args);
}
#Bean
public JsonMessageConverter jsonMessageConverter() {
ObjectMapper objectMapper = new ObjectMapper();
objectMapper.registerModule(new Hibernate5Module());
JacksonMapper jacksonMapper = new JacksonMapper(objectMapper);
return new JsonMessageConverter(jacksonMapper);
}
}
The documentation explain Gson is the default MessageConverter but it's not be clear how to change(more easy) gson to jackson.
https://docs.spring.io/spring-cloud-function/docs/current/reference/html/spring-cloud-function.html#_provided_messageconverters