HibernateException: Flush Pendant la cascade est dangereux

Parfois, je reçois une exception mal formée dans mon application. Les exceptions arrivent l'une après l'autre comme suit:

@SuppressWarnings("unchecked")
public Iterator findByCriteria(Criteria criteria, int first, int count) {
    LOGGER.debug("findByCriteria {}", criteria);
    setEntityManager(criteria.getDatabase());
    StringBuffer queryString = new StringBuffer();
    Query query;

    queryString.append("SELECT MAX(a.code), MIN(a.logTime), MAX(a.logTime), "
            + "a.transactionId as transactionId, a.sender as sender, a.receiver as receiver ");

    //Add the common where clause
    queryString.append(" FROM Audit a where a.logTime BETWEEN :from AND :to");
    // Append the appropriate addition where clauses depending on what
    // values are set 
    if (criteria.getSender() != null
            || criteria.getFilter().getSender() != null) {
        queryString.append(" AND a.sender = :sender");
    }

    if (criteria.getReceiver() != null
            || criteria.getFilter().getReceiver() != null) {
        queryString.append(" AND a.receiver = :receiver");
    }

    if (criteria.getMessageType() != null
            || criteria.getFilter().getMessageType() != null) {
        queryString.append(" AND a.messageType = :messageType");
    }
    if (criteria.getTransactionId() != null
            || criteria.getFilter().getTransactionId() != null) {
        queryString
                .append(" AND a.transactionId = :transactionId");
    }
    if (criteria.getKeyFieldValue() != null
            || criteria.getFilter().getKeyFieldValue() != null) {
        queryString
                .append(" AND UPPER(a.keyFieldValue) LIKE :keyFieldValue");
    }


    // We want a summary so lets group by the common ids
    queryString.append(" GROUP BY a.transactionId, a.sender, a.receiver ");

    // Add order by clause
    if (criteria.getOrderBy() != null) {
        queryString.append(" ORDER BY ");           
        queryString.append(criteria.getOrderBy());          
        queryString.append(criteria.isAscending() ? " ASC" : " DESC");
    }

    Session session = ((Session) em.getDelegate()).getSessionFactory().openSession();
    query = session.createQuery(queryString.toString());
    query.setReadOnly(true);
    query.setFetchSize(Integer.valueOf(1000));
    query.setCacheable(true);
    query.setCacheMode(CacheMode.NORMAL);

    // Will always have from and to dates
    query.setParameter("from", criteria.getFromDate());
    query.setParameter("to", criteria.getToDate());

    // Set remaining parameters depending on what is set
    if (criteria.getSender() != null) {
        query.setParameter("sender", criteria.getSenderValue());
    }

    // Override the search criteria with the filter if set
    if (criteria.getFilter().getSender() != null) {
        query.setParameter("sender", criteria.getFilter().getSender());
    }

    if (criteria.getReceiver() != null) {
        query.setParameter("receiver", criteria.getReceiverValue());
    }

    if (criteria.getFilter().getReceiver() != null) {
        query.setParameter("receiver", criteria.getFilter().getReceiver());
    }

    if (criteria.getMessageType() != null) {
        query.setParameter("messageType", criteria.getMessageTypeValue());
    }

    if (criteria.getFilter().getMessageType() != null) {
        query.setParameter("messageType", criteria.getFilter()
                .getMessageType());
    }
    if (criteria.getTransactionId() != null) {
        query.setParameter("transactionId", criteria.getTransactionId());
    }

    if (criteria.getFilter().getTransactionId() != null) {
        query.setParameter("transactionId", criteria.getFilter()
                .getTransactionId());
    }
    if (criteria.getKeyFieldValue() != null) {
        query.setParameter("keyFieldValue", "%"
                + criteria.getKeyFieldValue().toUpperCase() + "%");
    }

    if (criteria.getFilter().getKeyFieldValue() != null) {
        query.setParameter("keyFieldValue", "%"
                + criteria.getFilter().getKeyFieldValue().toUpperCase()
                + "%");
    }
    // Set the limits       
    query.setFirstResult(first);
    query.setMaxResults(PAGE_SIZE);

    Iterator iterator = query.list().iterator();
    session.close();
    return iterator;
}