ok, it works: https://github.com/droolsjbpm/jbpm/pull/143
change in Taskorm-JPA2.xml:
<named-query name="TasksByStatusByProcessIdByTaskName">
<query>
select
new org.jbpm.task.query.TaskSummary(
t.id,
t.taskData.processInstanceId,
name.text,
subject.text,
description.text,
t.taskData.status,
t.priority,
t.taskData.skipable,
actualOwner,
createdBy,
t.taskData.createdOn,
t.taskData.activationTime,
t.taskData.expirationTime,
t.taskData.processId,
t.taskData.processSessionId)
from
Task t
left join t.taskData.actualOwner as actualOwner
left join t.taskData.createdBy as createdBy
left join t.subjects as subject
left join t.descriptions as description
left join t.names as name
where
t.archived = 0 and
t.taskData.processInstanceId = :processInstanceId and
name.text = :taskName and
(
name.language = :language
or t.names.size = 0
) and
(
subject.language = :language
or t.subjects.size = 0
) and
(
description.language = :language
or t.descriptions.size = 0
) and
t.taskData.status in (:status) and
t.taskData.expirationTime is null
</query>
<!-- hint name="org.hibernate.timeout" value="200"/ -->
</named-query>