Indicate L2 cache usage via EM property

EmployeeManager.java

@Stateless
public class EmployeeManager{
  @persistenceContext("emp_PU")
  EntityManager em;
  
  public Employee getByID(String id){
    em.setProperty("javax.persistence.cache.retrieveMode", CacheRetrieveMode.USE); //look for the employee in the L2 cache first
    return em.find(Employee.class, id);
  }
}