Howto use methods of CrudRepository (or SimpleJpaRepository) in a Spring-Data-Repository-Fragment method?

Question

Goal: In order to make my Spring-Boot-Database code compatible with Android-Room-Database all my Spring-Boot-Repositoy classes should have a method insert(T entity) and update(T entity).

Following the guide from https://docs.spring.io/spring-data/jpa/docs/current/reference/html/#repositories.single-repository-behavior part Example 34. Fragments overriding and part Example 35. Customized repository interfaces I tried to implement the new insert method by calling the existing save method:

public class CustomRoomMethodsImpl<T,ID> ... {
    public void insert(T entity) {
         parent.save(entity);
    }
}

My Question: where does the Java-Fragment code CustomRoomMethodsImpl get parent from (that has already implemented the save method)?

When I tried to add a parameter to the Java-Fragment code constructor

public CustomRoomMethodsImpl(SimpleJpaRepository<T, ID> parent) {
    this.parent = parent;
}

I get the spring-boot error

Parameter 0 of constructor in org.fdroid.jpa.db.CustomRoomMethodsImpl required 
    a bean of type 'org.springframework.data.jpa.repository.support.SimpleJpaRepository' 
    that could not be found.


Action:

Consider defining a bean of type 
    'org.springframework.data.jpa.repository.support.SimpleJpaRepository' 
    in your configuration.

Since all my jpa repository classes should get their insert(T entity) and update(T entity) methods: how could i provide access to the genrated class (CrudRepository<T, ID> or SimpleJpaRepository<T, ID>) ?

---

Here is my implementation that caused the spring-boot-error:

// CustomRoomMethods.java: Interface for Spring-Data-repository-fragment methods

@NoRepositoryBean
public interface CustomRoomMethods<T,ID> {
    void insert(T entity);
    void update(T entity);
}

// CustomRoomMethodsImpl.java: Implementatoin of Interface for Spring-Data-repository-fragment methods

public class CustomRoomMethodsImpl<T,ID> implements CustomRoomMethods<T,ID> {
    private SimpleJpaRepository<T, ID> parent;

    public CustomRoomMethodsImpl(SimpleJpaRepository<T, ID> parent) {
        this.parent = parent;
    }

    @Override
    public void insert(T entity) {
        parent.save(entity);
    }

    @Override
    public void update(T entity) {
        parent.save(entity);
    }
}

// UserRepositoryJpa.java Example JPA Repository that save User-Pojo-entity to Database

@Repository
public interface UserRepositoryJpa extends CrudRepository<User, Integer>, CustomRoomMethods<User,Integer> {
}

// User.java Example User-Pojo-entity that should be saved to Database

@Entity
public class Test {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    public int id;

    public String name;
}

---

Background: I try to implement a database compatibility layer for Spring-Boot-JPA/Android-Room

• In Jpa pojo-entities are ẁritten to the database using repository.save(entity)
• In Android-Room pojo-entities are written to the database using dao.insert(entity) or dao.update(entity)

"compatibility layer" means my Service-layer-code is pure-non-android-code that can be used in android and in spring-boot. The Service-layer-code uses a common java-repository-interface that is either implemented in android-room or in JPA.