docs: protected EntityManagerFactory lookupEntityManagerFactory(OpenEntityManager openEntityManager) {
          String emfBeanName = openEntityManager.name();
          String puName = openEntityManager.unitName();
          if (StringUtils.hasLength(emfBeanName)) {
              return this.applicationContext.getBean(emfBeanName, EntityManagerFactory.class);
          } else if (!StringUtils.hasLength(puName)
                  && this.applicationContext.containsBean(
                          OpenEntityManagerInViewFilter.DEFAULT_ENTITY_MANAGER_FACTORY_BEAN_NAME)) {
              return this.applicationContext.getBean(
                      OpenEntityManagerInViewFilter.DEFAULT_ENTITY_MANAGER_FACTORY_BEAN_NAME,
                      EntityManagerFactory.class);
          } else {
              // Includes fallback search for single EntityManagerFactory bean by type.
              return EntityManagerFactoryUtils.findEntityManagerFactory(
                      this.applicationContext, puName);
          }
      }