@Override
    public void save(Visit visit) {
        if (visit.getId() == null) {
            this.em.persist(visit);
        } else {
            this.em.merge(visit);
        }
    }
JPA implementation of the ClinicService interface using EntityManager.
<p/>
<p>The mappings are defined in "orm.xml" located in the META-INF directory.

@author Mike Keith
@author Rod Johnson
@author Sam Brannen
@author Michael Isvy
@since 22.4.2006
src/main/java/org/springframework/samples/petclinic/repository/jpa/JpaVisitRepositoryImpl.java