Java Persistence API service created with plop cli

CustomerService.java

package de.ostfalia.groupfour.services;

import java.util.List;
import javax.ejb.Stateless;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;

@Stateless
public class CustomerService {
  @PersistenceContext
  protected EntityManager entityManager;

  public CustomerService() {
  }

  public void persist(Customer customer) {
    entityManager.persist(customer);
  }

  public Customer findById(int id) {
    return entityManager.find(Customer.class, id);
  }

  @SuppressWarnings("unchecked")
  public List<Customer> findAll() {
    String sqlQuery = "SELECT e FROM Customer e";
    List<Customer> allEntities = entityManager.createQuery(sqlQuery).getResultList();
    return allEntities;
  }

  public Customer delete(int id) {
    Customer entityToBeRemoved = findById(id);
    entityManager.remove(entityToBeRemoved);
    return entityToBeRemoved;
  }
}