in this function there is a hardcoded query string :

List<ProcessInstanceLog> result = getEntityManager().createQuery(
"from ProcessInstanceLog as log where log.processInstanceId = ? and log.end is null")
.setParameter(1, processInstanceId).getResultList();

it gives the following error:
<openjpa-2.0.1-r422266:989424 nonfatal user error> org.apache.openjpa.persistence.ArgumentException: "Encountered "from" at character 1, but expected: ["DELETE", "SELECT", "UPDATE"]." while parsing JPQL "from ProcessInstanceLog as log where log.processInstanceId = ? and log.end is null". See nested stack trace for original parse error.

Fix: use a named query and put it in orm.xml