List<ProcessInstanceRef> results = adoptProcessInstances(processInstances);
// add history info
// TODO: optimize w. batch query
HistoryService histService = this.processEngine.getHistoryService();
for(ProcessInstanceRef inst : results)
{
HistoryProcessInstanceQuery hQuery = histService.createHistoryProcessInstanceQuery();
hQuery.processInstanceId(inst.getId());
HistoryProcessInstance entry = hQuery.uniqueResult();
inst.setStartDate(entry.getStartTime());
}