code: @SuppressWarnings("unchecked")
      protected E get(Serializable id) {
          return (E) currentSession().get(entityClass, requireNonNull(id));
      }
docs: Return the persistent instance of {@code <E>} with the given identifier, or {@code null} if
  there is no such persistent instance. (If the instance, or a proxy for the instance, is
  already associated with the session, return that instance or proxy.)
  
  @param id an identifier
  @return a persistent instance or {@code null}
  @throws HibernateException
  @see Session#get(Class, Serializable)