Document attachments in a form or process

Hi,

I was trying to add document attachments based on https://access.redhat.com/documentation/en-us/red_hat_process_automation_manager/7.5/html/designing_business_processes_in_business_central/business-process-forms

I can attach a document in a form but the document was failed to be created in RHPAM:
15:03:41,462 ERROR [org.jbpm.document.service.impl.DocumentStorageServiceImpl] (default task-2) Error writing file D:\test\a.pdf: {}: java.io.IOException: Directory '.docs\388f4d34-b732-48d6-b898-d00fd8bb1cf3\D:\test' could not be created
at org.apache.commons.io.FileUtils.openOutputStream(FileUtils.java:361)
at org.apache.commons.io.FileUtils.writeByteArrayToFile(FileUtils.java:2222)
at org.apache.commons.io.FileUtils.writeByteArrayToFile(FileUtils.java:2186)
at org.apache.commons.io.FileUtils.writeByteArrayToFile(FileUtils.java:2171)
at org.jbpm.document.service.impl.DocumentStorageServiceImpl.saveDocument(DocumentStorageServiceImpl.java:87)
at org.jbpm.document.marshalling.DocumentMarshallingStrategy.marshal(DocumentMarshallingStrategy.java:73)
at org.jbpm.marshalling.impl.ProtobufProcessMarshaller.marshallVariable(ProtobufProcessMarshaller.java:269)
at org.jbpm.marshalling.impl.AbstractProtobufProcessInstanceMarshaller.writeProcessInstance(AbstractProtobufProcessInstanceMarshaller.java:164)
at org.jbpm.marshalling.impl.AbstractProtobufProcessInstanceMarshaller.writeProcessInstance(AbstractProtobufProcessInstanceMarshaller.java:75)
at org.jbpm.persistence.processinstance.ProcessInstanceInfo.transform(ProcessInstanceInfo.java:244)
at org.drools.persistence.TriggerUpdateTransactionSynchronization.beforeCompletion(TriggerUpdateTransactionSynchronization.java:61)
at org.drools.persistence.jta.JtaTransactionSynchronizationAdapter.beforeCompletion(JtaTransactionSynchronizationAdapter.java:54)
at org.jboss.as.txn.service.internal.tsr.JCAOrderedLastSynchronizationList.beforeCompletion(JCAOrderedLastSynchronizationList.java:113)
at org.wildfly.transaction.client.AbstractTransaction.performConsumer(AbstractTransaction.java:236)
at org.wildfly.transaction.client.AbstractTransaction.performConsumer(AbstractTransaction.java:247)
at org.wildfly.transaction.client.AbstractTransaction$AssociatingSynchronization.beforeCompletion(AbstractTransaction.java:292)
at com.arjuna.ats.internal.jta.resources.arjunacore.SynchronizationImple.beforeCompletion(SynchronizationImple.java:76)
at com.arjuna.ats.arjuna.coordinator.TwoPhaseCoordinator.beforeCompletion(TwoPhaseCoordinator.java:360)
at com.arjuna.ats.arjuna.coordinator.TwoPhaseCoordinator.end(TwoPhaseCoordinator.java:91)
at com.arjuna.ats.arjuna.AtomicAction.commit(AtomicAction.java:162)
at com.arjuna.ats.internal.jta.transaction.arjunacore.TransactionImple.commitAndDisassociate(TransactionImple.java:1287)
at com.arjuna.ats.internal.jta.transaction.arjunacore.BaseTransaction.commit(BaseTransaction.java:126)