ClassNotFoundException when calling taskService.getTaskContent() with PerProcessInstance in BPMS

Issue

• I get the following Exception after restarting BPMS server. The Exception gradually decrease.

06:52:55,574 WARN  [org.jbpm.services.task.utils.ContentMarshallerHelper] (HTTP-71) Exception while unmarshaling content: java.lang.ClassNotFoundException: com.example.MyPojo from [Module "org.jbpm:main" from local module loader @68e2918b (finder: local module finder @72c17278 (roots: /opt/jbpm/jboss-eap-6.1/modules,/opt/jbpm/jboss-eap-6.1/modules/system/layers/bpms,/opt/jbpm/jboss-eap-6.1/modules/system/layers/base))]
        at org.jboss.modules.ModuleClassLoader.findClass(ModuleClassLoader.java:196) [jboss-modules.jar:1.2.2.Final-redhat-1]
        at org.jboss.modules.ConcurrentClassLoader.performLoadClassUnchecked(ConcurrentClassLoader.java:444) [jboss-modules.jar:1.2.2.Final-redhat-1]
        at org.jboss.modules.ConcurrentClassLoader.performLoadClassChecked(ConcurrentClassLoader.java:432) [jboss-modules.jar:1.2.2.Final-redhat-1]
        at org.jboss.modules.ConcurrentClassLoader.performLoadClass(ConcurrentClassLoader.java:374) [jboss-modules.jar:1.2.2.Final-redhat-1]
        at org.jboss.modules.ConcurrentClassLoader.loadClass(ConcurrentClassLoader.java:119) [jboss-modules.jar:1.2.2.Final-redhat-1]
        at java.lang.Class.forName0(Native Method) [rt.jar:1.7.0_67]
        at java.lang.Class.forName(Class.java:270) [rt.jar:1.7.0_67]
        at org.drools.core.common.DroolsObjectInputStream.resolveClass(DroolsObjectInputStream.java:85)
        at org.drools.core.common.DroolsObjectInputStream.resolveClass(DroolsObjectInputStream.java:97)
        at java.io.ObjectInputStream.readNonProxyDesc(ObjectInputStream.java:1612) [rt.jar:1.7.0_67]
        at java.io.ObjectInputStream.readClassDesc(ObjectInputStream.java:1517) [rt.jar:1.7.0_67]
        at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1771) [rt.jar:1.7.0_67]
        at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1350) [rt.jar:1.7.0_67]
        at java.io.ObjectInputStream.readObject(ObjectInputStream.java:370) [rt.jar:1.7.0_67]
        at java.util.ArrayList.readObject(ArrayList.java:771) [rt.jar:1.7.0_67]
        at sun.reflect.GeneratedMethodAccessor152.invoke(Unknown Source) [:1.7.0_67]
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) [rt.jar:1.7.0_67]
        at java.lang.reflect.Method.invoke(Method.java:606) [rt.jar:1.7.0_67]
        at java.io.ObjectStreamClass.invokeReadObject(ObjectStreamClass.java:1017) [rt.jar:1.7.0_67]
        at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1893) [rt.jar:1.7.0_67]
        at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1798) [rt.jar:1.7.0_67]
        at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1350) [rt.jar:1.7.0_67]
        at java.io.ObjectInputStream.readObject(ObjectInputStream.java:370) [rt.jar:1.7.0_67]
        at org.drools.core.marshalling.impl.SerializablePlaceholderResolverStrategy$SerializablePlaceholderStrategyContext.read(SerializablePlaceholderResolverStrategy.java:93)
        at org.drools.core.marshalling.impl.PersisterHelper.loadStrategiesIndex(PersisterHelper.java:296)
        at org.drools.core.marshalling.impl.PersisterHelper.loadStrategiesCheckSignature(PersisterHelper.java:245)
        at org.drools.core.marshalling.impl.PersisterHelper.readFromStreamWithHeaderPreloaded(PersisterHelper.java:261)
        at org.jbpm.services.task.utils.ContentMarshallerHelper.unmarshall(ContentMarshallerHelper.java:105)
        at org.jbpm.services.task.commands.GetTaskContentCommand.execute(GetTaskContentCommand.java:42)
        at org.jbpm.services.task.commands.GetTaskContentCommand.execute(GetTaskContentCommand.java:16)
        at org.kie.remote.services.util.ExecuteAndSerializeCommand.execute(ExecuteAndSerializeCommand.java:26)
        at org.jbpm.services.task.commands.TaskCommandExecutorImpl$SelfExecutionCommandService.execute(TaskCommandExecutorImpl.java:65)
        at org.drools.core.command.impl.AbstractInterceptor.executeNext(AbstractInterceptor.java:41)
        at org.jbpm.services.task.persistence.TaskTransactionInterceptor.execute(TaskTransactionInterceptor.java:54)
        at org.jbpm.services.task.commands.TaskCommandExecutorImpl.execute(TaskCommandExecutorImpl.java:40)
        at org.jbpm.services.task.impl.command.CommandBasedTaskService.execute(CommandBasedTaskService.java:128)
        at org.kie.remote.services.cdi.ProcessRequestBean.doTaskOperation(ProcessRequestBean.java:249)
        at org.kie.remote.services.cdi.ProcessRequestBean.processCommand(ProcessRequestBean.java:121)
        at org.kie.remote.services.cdi.ProcessRequestBean$Proxy$_$$_WeldClientProxy.processCommand(ProcessRequestBean$Proxy$_$$_WeldClientProxy.java)
        at org.kie.remote.services.rest.ResourceBase.restProcessJaxbCommandsRequest(ResourceBase.java:69)
...