docs: @Override
      public ProcessInstanceLog findProcessInstance(long processInstanceId) {
          EntityManager em = getEntityManager();
          Object newTx = joinTransaction(em);
          try {
          	return (ProcessInstanceLog) em
          	        .createQuery("FROM ProcessInstanceLog p WHERE p.processInstanceId = :processInstanceId")
          	        .setParameter("processInstanceId", processInstanceId).getSingleResult();
          } catch (NoResultException e) {
          	return null;
          } finally {
          	closeEntityManager(em, newTx);
          }
      }