Hi.
   I use human task in JPA,when i call MinaTaskClient.complete throw below error:
java.lang.NullPointerException
 at org.drools.persistence.processinstance.JPAWorkItemManager.completeWorkItem(JPAWorkItemManager.java:83)
 at org.drools.process.workitem.wsht.WSHumanTaskHandler$GetCompletedTaskResponseHandler.execute(WSHumanTaskHandler.java:282)
 at org.drools.task.service.TaskClientHandler.messageReceived(TaskClientHandler.java:67)
 at org.apache.mina.core.filterchain.DefaultIoFilterChain$TailFilter.messageReceived(DefaultIoFilterChain.java:752)
 at org.apache.mina.core.filterchain.DefaultIoFilterChain.callNextMessageReceived(DefaultIoFilterChain.java:414)2009-9-2 13:50:26 org.apache.mina.filter.logging.LogLevel$4 log
 at org.apache.mina.core.filterchain.DefaultIoFilterChain.access$1200(DefaultIoFilterChain.java:49)
 at org.apache.mina.core.filterchain.DefaultIoFilterChain$EntryImpl$1.messageReceived(DefaultIoFilterChain.java:832)
 at org.apache.mina.filter.codec.ProtocolCodecFilter$ProtocolDecoderOutputImpl.flush(ProtocolCodecFilter.java:379)
 at org.apache.mina.filter.codec.ProtocolCodecFilter.messageReceived(ProtocolCodecFilter.java:173)
 at org.apache.mina.core.filterchain.DefaultIoFilterChain.callNextMessageReceived(DefaultIoFilterChain.java:414)
 at org.apache.mina.core.filterchain.DefaultIoFilterChain.access$1200(DefaultIoFilterChain.java:49)
 at org.apache.mina.core.filterchain.DefaultIoFilterChain$EntryImpl$1.messageReceived(DefaultIoFilterChain.java:832)
 at org.apache.mina.core.filterchain.DefaultIoFilterChain$HeadFilter.messageReceived(DefaultIoFilterChain.java:616)
 at org.apache.mina.core.filterchain.DefaultIoFilterChain.callNextMessageReceived(DefaultIoFilterChain.java:414)
 at org.apache.mina.core.filterchain.DefaultIoFilterChain.fireMessageReceived(DefaultIoFilterChain.java:408)
 at org.apache.mina.core.polling.AbstractPollingIoProcessor.read(AbstractPollingIoProcessor.java:578)
 at org.apache.mina.core.polling.AbstractPollingIoProcessor.process(AbstractPollingIoProcessor.java:540)
 at org.apache.mina.core.polling.AbstractPollingIoProcessor.process(AbstractPollingIoProcessor.java:532)
 at org.apache.mina.core.polling.AbstractPollingIoProcessor.access$400(AbstractPollingIoProcessor.java:58)
 at org.apache.mina.core.polling.AbstractPollingIoProcessor$Worker.run(AbstractPollingIoProcessor.java:857)
 at org.apache.mina.util.NamePreservingRunnable.run(NamePreservingRunnable.java:51)
 at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(Unknown Source)
 at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
 at java.lang.Thread.run(Unknown Source)