Description of problem:

If a user application uses LocalTaskService with transaction-type="JTA" persistence-unit, org.jbpm.task.service.TaskService.createSession() fails with NameNotFoundException.

[10/17/13 18:17:33:092 IST] 000000ea SystemOut     O 18:17:33,092 ERROR TaskService:429 - Unable to find transaction: A JNDI operation on a "java:" name cannot be completed because the server runtime is not able to associate the operation's thread with any J2EE application component.  This condition can occur when the JNDI client using the "java:" name is not executed on the thread of a server application request.  Make sure that a J2EE application does not execute JNDI operations on "java:" names within static code blocks or in threads created by that J2EE application.  Such code does not necessarily run on the thread of a server application request and therefore is not supported by JNDI operations on "java:" names.
java.lang.IllegalStateException: Unable to find transaction: A JNDI operation on a "java:" name cannot be completed because the server runtime is not able to associate the operation's thread with any J2EE application component.  This condition can occur when the JNDI client using the "java:" name is not executed on the thread of a server application request.  Make sure that a J2EE application does not execute JNDI operations on "java:" names within static code blocks or in threads created by that J2EE application.  Such code does not necessarily run on the thread of a server application request and therefore is not supported by JNDI operations on "java:" names.
        at org.drools.persistence.jta.JtaTransactionManager.findUserTransaction(JtaTransactionManager.java:124)
        at org.drools.persistence.jta.JtaTransactionManager.<init>(JtaTransactionManager.java:69)
        at org.jbpm.task.service.persistence.TaskJTATransactionManager.<init>(TaskJTATransactionManager.java:37)
        at org.jbpm.task.service.persistence.TaskSessionFactoryImpl.createTaskPersistenceManager(TaskSessionFactoryImpl.java:85)
        at org.jbpm.task.service.persistence.TaskSessionFactoryImpl.createTaskServiceSession(TaskSessionFactoryImpl.java:75)
        at org.jbpm.task.service.TaskService.createSession(TaskService.java:203)
        at org.jbpm.task.service.TaskService.executeEscalatedDeadline(TaskService.java:288)
        at org.jbpm.task.service.TaskService$ScheduledTaskDeadline.call(TaskService.java:426)
        at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:314)
        at java.util.concurrent.FutureTask.run(FutureTask.java:149)
        at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.access$301(ScheduledThreadPoolExecutor.java:109)
        at java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask.run(ScheduledThreadPoolExecutor.java:217)
        at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:897)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:919)
        at java.lang.Thread.run(Thread.java:770)
Caused by: javax.naming.ConfigurationException: A JNDI operation on a "java:" name cannot be completed because the server runtime is not able to associate the operation's thread with any J2EE application component.  This condition can occur when the JNDI client using the "java:" name is not executed on the thread of a server application request.  Make sure that a J2EE application does not execute JNDI operations on "java:" names within static code blocks or in threads created by that J2EE application.  Such code does not necessarily run on the thread of a server application request and therefore is not supported by JNDI operations on "java:" names. [Root exception is javax.naming.NameNotFoundException: Name "comp/UserTransaction" not found in context "java:".]
        at com.ibm.ws.naming.java.javaURLContextImpl.throwExceptionIfDefaultJavaNS(javaURLContextImpl.java:522)
        at com.ibm.ws.naming.java.javaURLContextImpl.throwConfigurationExceptionWithDefaultJavaNS(javaURLContextImpl.java:552)
        at com.ibm.ws.naming.java.javaURLContextImpl.lookupExt(javaURLContextImpl.java:481)
        at com.ibm.ws.naming.java.javaURLContextRoot.lookupExt(javaURLContextRoot.java:485)
        at com.ibm.ws.naming.java.javaURLContextRoot.lookup(javaURLContextRoot.java:370)
        at org.apache.aries.jndi.DelegateContext.lookup(DelegateContext.java:161)
        at javax.naming.InitialContext.lookup(InitialContext.java:436)
        at org.drools.persistence.jta.JtaTransactionManager.findUserTransaction(JtaTransactionManager.java:119)
        ... 14 more
Caused by: javax.naming.NameNotFoundException: Name "comp/UserTransaction" not found in context "java:".
        at com.ibm.ws.naming.ipbase.NameSpace.lookupInternal(NameSpace.java:1228)
        at com.ibm.ws.naming.ipbase.NameSpace.lookup(NameSpace.java:1141)
        at com.ibm.ws.naming.urlbase.UrlContextImpl.lookupExt(UrlContextImpl.java:1436)
        at com.ibm.ws.naming.java.javaURLContextImpl.lookupExt(javaURLContextImpl.java:477)
        ... 19 more

Steps to Reproduce:
1. Use persistence.xml with transaction-type="JTA"
2. Instantiate a LocalTaskService
Environment env = ksession.getEnvironment();
EntityManagerFactory emf = (EntityManagerFactory) env.get(EnvironmentName.ENTITY_MANAGER_FACTORY);
org.jbpm.task.service.TaskService taskService = new org.jbpm.task.service.TaskService(emf, SystemEventListenerFactory.getSystemEventListener());
LocalTaskService localTaskService = new LocalTaskService(taskService);

Actual results:

javax.naming.NameNotFoundException: Name "comp/UserTransaction" not found in context "java:".

Expected results:

No exception