I’m currently doing a proof of concept for an hexagonal architecture in which I have three main modules as the following tree project shows :

Architecture hexagonale/
    Business/
        Model/
            Prm
        Ports/
            PrmPort (interface)
            PrmRepository (interface)
        Service/
            PrmService (interface)
            PrmServiceImpl (implements PrmService)
            ServiceFactory (create new PrmServiceImpl)
    Exposition
        Adapters/
            PrmAdapter (implements PrmPort from Business)
        Api/
            PrmController
        Application
        ApplicationConfig (@Configuration, @Bean)
    Infrastructure
        Adapters/
            PrmAdapter (implements PrmRepository from Business) : the goal is to convert data retrieved from Database which is Prm (Infrastructure) to Prm (Business type)
        Models/
            Prm
        Repositories/
            PrmRepository (interface extends JpaRepository)

The problem I’m trying to solve now is that I need to retrieve data from my database

Architecture_Hexagonale/Infrastructure/Repositories/PrmRepository.java:

package fr.enedis.icam.microapp.sample.business.ports;

import fr.enedis.icam.microapp.sample.business.model.Prm;

import java.util.List;

public interface PrmRepository {
    List<Prm> findAll();
}

and to do so I use my PrmAdapter from Infrastructure as following

Architecture_Hexagonale/Infrastructure/Adapters/PrmAdapter.java: **

package fr.enedis.icam.microapp.sample.infrastructure.adapters;

import fr.enedis.icam.microapp.sample.business.model.Prm;
import fr.enedis.icam.microapp.sample.business.ports.PrmRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;


import java.util.ArrayList;
import java.util.List;

@Service
public class PrmAdapter implements PrmRepository {
    public fr.enedis.icam.microapp.sample.infrastructure.repositories.PrmRepository repo;

    public List<Prm> findAll() {
        List<fr.enedis.icam.microapp.sample.infrastructure.models.Prm> infraList = repo.findAll();
        List<Prm> toRet = new ArrayList<>();

        for (fr.enedis.icam.microapp.sample.infrastructure.models.Prm prm : infraList) {
            toRet.add(prm.convert());
        }
        return toRet;
    }
}

The problem is the public fr.enedis.icam.microapp.sample.infrastructure.repositories.PrmRepository repo; is not initialized and returns a NullPointer.** It has to be noted that my business Module doesn't depend of any external components such as databases, framework or any kind of.    I already tried something like: 

package fr.enedis.icam.microapp.sample.infrastructure.adapters;

import fr.enedis.icam.microapp.sample.business.model.Prm;
import fr.enedis.icam.microapp.sample.business.ports.PrmRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.ArrayList;import java.util.List;

@Service
public class PrmAdapter implements PrmRepository {
@Autowiredprivate fr.enedis.icam.microapp.sample.infrastructure.repositories.PrmRepository repo;

public List<Prm> findAll() {     
    List<fr.enedis.icam.microapp.sample.infrastructure.models.Prm> infraList = repo.findAll();    

    List<Prm> toRet = new ArrayList<>();      
    for (fr.enedis.icam.microapp.sample.infrastructure.models.Prm prm : infraList) {         
        toRet.add(prm.convert());     
    }     
    return toRet; 
}

}

package fr.enedis.icam.microapp.sample.application;

import fr.enedis.icam.microapp.sample.application.adapters.PrmAdapter;
import fr.enedis.icam.microapp.sample.business.ports.PrmPort;
import fr.enedis.icam.microapp.sample.business.ports.PrmRepository;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;

@Configuration
//@EnableJpaRepositories(basePackages = “fr.enedis.icam.microapp.sample.infrastructure.repositories”)
public class ApplicationConfig {
@Bean public PrmPort prmPort() {
return new PrmAdapter();
}

@Bean public PrmRepository prmRepository(){     
    return new fr.enedis.icam.microapp.sample.infrastructure.adapters.PrmAdapter(); 
}

}

But this method gives me missing bean for repository. I also tried using 

package fr.enedis.icam.microapp.sample.application;

import fr.enedis.icam.microapp.sample.application.adapters.PrmAdapter;
import fr.enedis.icam.microapp.sample.business.ports.PrmPort;
import fr.enedis.icam.microapp.sample.business.ports.PrmRepository;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.data.jpa.repository.config.EnableJpaRepositories;

@Configuration@EnableJpaRepositories(basePackages = “fr.enedis.icam.microapp.sample.infrastructure.repositories”)
public class ApplicationConfig {

@Bean
public PrmPort prmPort() {
    return new PrmAdapter();
}

@Bean
public PrmRepository prmRepositoryImpl(){
    return new fr.enedis.icam.microapp.sample.infrastructure.adapters.PrmAdapter();
}

}