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Eclipse debugging for null pointer exception

I am getting a NullPointerException as shown below.
However, the debugger is not able to bring it up when enabled in this method, the code is getting invoked with reflections. Can you please provide me ideas\techniques to be able to debug this code?
[10/18/16 18:20:47:933 EST] 00000051 DWLExceptionU E java.lang.NullPointerException
at com.dwl.base.notification.NotificationManager$NotificationChannel.notify(NotificationManager.java:662)
at com.dwl.base.notification.NotificationManager$NotificationType.notify(NotificationManager.java:402)
at com.dwl.base.notification.NotificationManager.notify(NotificationManager.java:1454)
at com.dwl.base.notification.bean.impl.NotificationBean.notify(NotificationBean.java:142)
at com.dwl.base.notification.EJSLocalCSLNotification_e2801c59.notify(EJSLocalCSLNotification_e2801c59.java)
at com.dwl.base.notification.EJSProxy$$NotificationLocal.notify(Unknown Source)
at au.com.xxxxx.mdm.notification.NotificationHelper.sendNotification(NotificationHelper.java:75)
at au.com.xxxxxx.mdm.behaviour.SingleCustomerViewId.triggerNotification(SingleCustomerViewId.java:159)
at au.com.xxxxxxx.mdm.behaviour.SingleCustomerViewId.execute(SingleCustomerViewId.java:129)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:88)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:55)
at java.lang.reflect.Method.invoke(Method.java:613)
at com.dwl.base.extensionFramework.JavaExtensionSet.invoke(JavaExtensionSet.java:159)
at com.dwl.base.extensionFramework.ExtensionHandler.executeExtension(ExtensionHandler.java:251)
at com.dwl.base.DWLCommonComponent.handleExtensions(DWLCommonComponent.java:1380)
at com.dwl.base.DWLCommonComponent.postExecute(DWLCommonComponent.java:509)
at com.dwl.tcrm.common.TCRMCommonComponent.postExecute(TCRMCommonComponent.java:263)
at com.dwl.tcrm.coreParty.component.TCRMPersonComponent.addPerson(TCRMPersonComponent.java:1641)
at com.dwl.tcrm.coreParty.component.TCRMPartyComponent.addPerson(TCRMPartyComponent.java:3079)
at com.dwl.tcrm.coreParty.component.TCRMPartyComponent.addPartySimple(TCRMPartyComponent.java:2813)
at com.dwl.tcrm.coreParty.component.TCRMPartyComponent.addParty(TCRMPartyComponent.java:2471)
at com.dwl.tcrm.coreParty.controller.TCRMCorePartyTxnBean.addPerson(TCRMCorePartyTxnBean.java:1764)
at Proxy5aa32899_c04f_46c5_9706_69af241cd3c4.addPerson(Unknown Source)
at Proxy5aa32899_c04f_46c5_9706_69af241cd3c4.addPerson(Unknown Source)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:88)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:55)
at java.lang.reflect.Method.invoke(Method.java:613)
at com.dwl.base.requestHandler.DWLTxnBP.processPersistentObject(DWLTxnBP.java:262)
at com.dwl.base.requestHandler.DWLTxnBP.execute(DWLTxnBP.java:115)
at com.dwl.base.requestHandler.DWLTxnProcessor.processTx(DWLTxnProcessor.java:98)
at com.dwl.unifi.tx.manager.CTxRxFacade.processTxNormal(CTxRxFacade.java:681)
at com.dwl.unifi.tx.manager.CTxRxFacade.processTx(CTxRxFacade.java:544)
at com.dwl.base.requestHandler.DWLRequestHandler.processTransaction(DWLRequestHandler.java:1187)
at com.dwl.base.requestHandler.DWLRequestHandler.processTx(DWLRequestHandler.java:591)
at com.dwl.base.requestHandler.DWLServiceControllerBase.processRequest(DWLServiceControllerBase.java:253)
at com.dwl.base.requestHandler.beans.EJSRemoteCSLDWLServiceController_2c54996d.processRequest(EJSRemoteCSLDWLServiceController_2c54996d.java)
at com.dwl.base.requestHandler.beans._EJSRemoteCSLDWLServiceController_2c54996d_Tie.processRequest(_EJSRemoteCSLDWLServiceController_2c54996d_Tie.java:1)
at com.dwl.base.requestHandler.beans._EJSRemoteCSLDWLServiceController_2c54996d_Tie._invoke(_EJSRemoteCSLDWLServiceController_2c54996d_Tie.java)
at com.ibm.CORBA.iiop.ServerDelegate.dispatchInvokeHandler(ServerDelegate.java:669)
at com.ibm.CORBA.iiop.ServerDelegate.dispatch(ServerDelegate.java:523)
at com.ibm.rmi.iiop.ORB.process(ORB.java:523)
at com.ibm.CORBA.iiop.ORB.process(ORB.java:1575)
at com.ibm.rmi.iiop.Connection.doRequestWork(Connection.java:3039)
at com.ibm.rmi.iiop.Connection.doWork(Connection.java:2922)
at com.ibm.rmi.iiop.WorkUnitImpl.doWork(WorkUnitImpl.java:64)
at com.ibm.ejs.oa.pool.PooledThread.run(ThreadPool.java:118)
at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:1892)

Can you please provide me ideas\techniques to be able to debug this code?
Since you said the method is called from reflection, you can see that in the stacktrace.
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:88)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:55)
at java.lang.reflect.Method.invoke(Method.java:613)
So, keep reading up from that.
I'm guessing you intentionally edited the xxxx values, so these are your libraries that are being dynamically called.
at au.com.xxxxx.mdm.notification.NotificationHelper.sendNotification(NotificationHelper.java:75)
at au.com.xxxxxx.mdm.behaviour.SingleCustomerViewId.triggerNotification(SingleCustomerViewId.java:159)
at au.com.xxxxxxx.mdm.behaviour.SingleCustomerViewId.execute(SingleCustomerViewId.java:129)
Then, the rest of the call stack just goes through some other code library within the same package.
at com.dwl.base.notification.NotificationManager$NotificationChannel.notify(NotificationManager.java:662)
at com.dwl.base.notification.NotificationManager$NotificationType.notify(NotificationManager.java:402)
at com.dwl.base.notification.NotificationManager.notify(NotificationManager.java:1454)
at com.dwl.base.notification.bean.impl.NotificationBean.notify(NotificationBean.java:142)
at com.dwl.base.notification.EJSLocalCSLNotification_e2801c59.notify(EJSLocalCSLNotification_e2801c59.java)
at com.dwl.base.notification.EJSProxy$$NotificationLocal.notify(Unknown Source)
So, the problem definitely starts at NotificationHelper.sendNotification(NotificationHelper.java:75), but it cannot easily be determined the path that the code took in order to reach its eventual destination or what exactly caused the exception without inspecting the source of (NotificationManager.java:662)

Hadoop Configuration Error

I am attempting to start up my hadoop application, however upon startup i am seeing this in the log files, does anyone have a clue as to what the problem is?
Creating filesystem for hdfs://10.170.4.141:9000
java.io.IOException: config()
at org.apache.hadoop.conf.Configuration.(Configuration.java:229)
at org.apache.hadoop.conf.Configuration.(Configuration.java:216)
at org.apache.hadoop.security.SecurityUtil.(SecurityUtil.java:60)
at org.apache.hadoop.net.NetUtils.makeSocketAddr(NetUtils.java:188)
at org.apache.hadoop.net.NetUtils.createSocketAddr(NetUtils.java:168)
at org.apache.hadoop.hdfs.server.namenode.NameNode.getAddress(NameNode.java:198)
at org.apache.hadoop.hdfs.DistributedFileSystem.initialize(DistributedFileSystem.java:88)
at org.apache.hadoop.fs.FileSystem.createFileSystem(FileSystem.java:1413)
at org.apache.hadoop.fs.FileSystem.access$200(FileSystem.java:68)
at org.apache.hadoop.fs.FileSystem$Cache.get(FileSystem.java:1431)
at org.apache.hadoop.fs.FileSystem.get(FileSystem.java:256)
at org.apache.hadoop.fs.FileSystem.get(FileSystem.java:125)
at org.apache.hadoop.fs.FileSystem.get(FileSystem.java:240)
at org.apache.hadoop.fs.Path.getFileSystem(Path.java:187)
at org.apache.hadoop.mapreduce.lib.input.FileInputFormat.addInputPath(FileInputFormat.java:372)
at org.blismedia.VolumeReportGenerateUpdates.main(VolumeReportGenerateUpdates.java:156)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.hadoop.util.RunJar.main(RunJar.java:187)

I think you're running into HADOOP-2851. This "error" can safely be ignored.
Apparently, Configuration's constructor logs an exception to the debug log, despite no exception actually being thrown. Why? Your guess is as good as mine. But the issue is resolved in their project as won't fix. "It's a feature, not a bug."
public Configuration(boolean loadDefaults) {
if (LOG.isDebugEnabled()) {
LOG.debug(StringUtils.stringifyException(new IOException("config()")));
}
// ...
}

Understanding Hibernate: JDBCExceptionReporter | Invalid parameter index

I am getting the following error when ever I try update particular information in a database, I have been looking online for a good bit now but I have been unable to find anywhere that explains what exactly the error is and what causes this error
2012-06-29 14:50:02,193 [project] ERROR [http-8080-2] JDBCExceptionReporter | Invalid parameter index 57.
2012-06-29 14:50:02,209 [project] ERROR [http-8080-2] AbstractFlushingEventListener | Could not synchronize database state with session
org.hibernate.exception.SQLGrammarException: could not update: [com.company.project.PSDBusinessAssociate#18962]
at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:67)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43)
at org.hibernate.persister.entity.AbstractEntityPersister.update(AbstractEntityPersister.java:2360)
at org.hibernate.persister.entity.AbstractEntityPersister.updateOrInsert(AbstractEntityPersister.java:2242)
at org.hibernate.persister.entity.AbstractEntityPersister.update(AbstractEntityPersister.java:2542)
at org.hibernate.action.EntityUpdateAction.execute(EntityUpdateAction.java:92)
at org.hibernate.engine.ActionQueue.execute(ActionQueue.java:248)
at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:232)
at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:140)
at org.hibernate.event.def.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:298)
at org.hibernate.event.def.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:27)
at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:1000)
at org.hibernate.impl.SessionImpl.managedFlush(SessionImpl.java:338)
at org.hibernate.transaction.JDBCTransaction.commit(JDBCTransaction.java:106)
at org.springframework.orm.hibernate3.HibernateTransactionManager.doCommit(HibernateTransactionManager.java:655)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.processCommit(AbstractPlatformTransactionManager.java:709)
at org.springframework.transaction.support.AbstractPlatformTransactionManager.commit(AbstractPlatformTransactionManager.java:678)
at org.springframework.transaction.interceptor.TransactionAspectSupport.commitTransactionAfterReturning(TransactionAspectSupport.java:321)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:116)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:171)
at org.springframework.aop.framework.Cglib2AopProxy$DynamicAdvisedInterceptor.intercept(Cglib2AopProxy.java:635)
at com.fexco.wuams.service.dwr.BusinessAssociateFormService$$EnhancerByCGLIB$$cb75a250.updateBusinessAssociate(<generated>)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.directwebremoting.impl.DefaultRemoter$1.doFilter(DefaultRemoter.java:740)
at org.directwebremoting.impl.DefaultRemoter.execute(DefaultRemoter.java:744)
at org.directwebremoting.impl.DefaultRemoter.execute(DefaultRemoter.java:593)
at org.directwebremoting.dwrp.BaseCallHandler.handle(BaseCallHandler.java:90)
at org.directwebremoting.servlet.UrlProcessor.handle(UrlProcessor.java:120)
at org.directwebremoting.servlet.DwrServlet.doPost(DwrServlet.java:141)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:641)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:265)
at org.acegisecurity.intercept.web.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:107)
at org.acegisecurity.intercept.web.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:72)
at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:275)
at org.acegisecurity.ui.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:124)
at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:275)
at org.acegisecurity.ui.AbstractProcessingFilter.doFilter(AbstractProcessingFilter.java:271)
at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:275)
at org.acegisecurity.context.HttpSessionContextIntegrationFilter.doFilter(HttpSessionContextIntegrationFilter.java:249)
at org.acegisecurity.util.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:275)
at org.acegisecurity.util.FilterChainProxy.doFilter(FilterChainProxy.java:149)
at org.acegisecurity.util.FilterToBeanProxy.doFilter(FilterToBeanProxy.java:98)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:228)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:105)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:212)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:818)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:624)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:445)
at java.lang.Thread.run(Thread.java:619)
Caused by: java.sql.SQLException: Invalid parameter index 57.
at net.sourceforge.jtds.jdbc.JtdsPreparedStatement.getParameter(JtdsPreparedStatement.java:255)
at net.sourceforge.jtds.jdbc.JtdsPreparedStatement.setParameter(JtdsPreparedStatement.java:326)
at net.sourceforge.jtds.jdbc.JtdsPreparedStatement.setLong(JtdsPreparedStatement.java:509)
at com.mchange.v2.c3p0.impl.NewProxyPreparedStatement.setLong(NewProxyPreparedStatement.java:703)
at org.hibernate.type.LongType.set(LongType.java:42)
at org.hibernate.type.NullableType.nullSafeSet(NullableType.java:83)
at org.hibernate.type.NullableType.nullSafeSet(NullableType.java:60)
at org.hibernate.type.ManyToOneType.nullSafeSet(ManyToOneType.java:78)
at org.hibernate.persister.entity.AbstractEntityPersister.dehydrate(AbstractEntityPersister.java:1932)
at org.hibernate.persister.entity.AbstractEntityPersister.update(AbstractEntityPersister.java:2306)
... 57 more
this appears in my error output on screen
could not update: [com.company.project.dataobject.PSDBusinessAssociate#18962]; nested exception is org.hibernate.exception.SQLGrammarException: could not update: [com.company.project.dataobject.PSDBusinessAssociate#18962]
so my question is what exactly does this error mean and what causes this error to occur?

This looks like the SQL that hibernate is generating isn't valid. This can often mean that your mappings are incorrect (such as incorrect column/table names). A good way to debug SQL Grammer exceptions is to set hibernate.show_sql=true and hibernate.format_sql=true in your SessionFactory. Hibernate will output generated sql to the console for you to verify.

Have you tried rebuilding your database through a Hibernate command? (I know Netbeans allows you to do this, dunno if it runs an ant script behind the scenes...) and seeing if it works?
Maybe someone edited the database manually without you knowing (or you yourself!) and Hibernate finds a table structure different than it is expecting when accessing the database...

What type of connections "RMI TCP Connection(idle)" threads correspond to?

I'm working on a distributed system which is RMI based using jdk1.6.
Occasionally I can see ConcurrentModificationException errors on that thread happening within the RMI runtime when it fails to serialize objects. I can reproduce that exception easily by concurrently updating object being returned from remote method.
But the problem is that I can't find the source of those calls. RMI exception is written to stderr (captured on server side within runtime code after it exits remote object method), but there are no matching exception in client services (while if that was a legitimate remote call, RemoteException with appropriate cause would be raised).
The only different thing about those exceptions is that they are happening on "RMI TCP Connection(idle)" thread and not on a thread like "RMI TCP Connection(<connection count>)-<client endpoint info>".
Any clues on what are those "idle" threads in RMI? I failed to find such within the openjdk sources.
Upd: I'm adding an exception stack trace as reproduced, which is what you usually see in described situation.
Server side console shows:
Exception dispatching call to [-3534448f:12f54948b7f:-7fff, 349678755005857493] in thread "RMI TCP Connection(6)-x.x.x.x" at Thu Apr 14 16:15:13 BST 2011:
java.util.ConcurrentModificationException
at java.util.ArrayList.writeObject(ArrayList.java:573)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:945)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1469)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1400)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1158)
at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:330)
at sun.rmi.server.UnicastRef.marshalValue(UnicastRef.java:274)
at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:315)
at sun.rmi.transport.Transport$1.run(Transport.java:159)
at java.security.AccessController.doPrivileged(Native Method)
at sun.rmi.transport.Transport.serviceCall(Transport.java:155)
at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:535)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:790)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:649)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662)
Client size exception thrown to caller:
java.rmi.UnmarshalException: error unmarshalling return; nested exception is:
java.io.EOFException
at sun.rmi.server.UnicastRef.invoke(UnicastRef.java:173)
at java.rmi.server.RemoteObjectInvocationHandler.invokeRemoteMethod(RemoteObjectInvocationHandler.java:178)
at java.rmi.server.RemoteObjectInvocationHandler.invoke(RemoteObjectInvocationHandler.java:132)
at $Proxy0.getData(Unknown Source)
at Clnt.main(Clnt.java:11)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:115)
Caused by: java.io.EOFException
at java.io.ObjectInputStream$BlockDataInputStream.peekByte(ObjectInputStream.java:2553)
at java.io.ObjectInputStream.skipCustomData(ObjectInputStream.java:1899)
at java.io.ObjectInputStream.readSerialData(ObjectInputStream.java:1873)
at java.io.ObjectInputStream.readOrdinaryObject(ObjectInputStream.java:1752)
at java.io.ObjectInputStream.readObject0(ObjectInputStream.java:1328)
at java.io.ObjectInputStream.readObject(ObjectInputStream.java:350)
at sun.rmi.server.UnicastRef.unmarshalValue(UnicastRef.java:306)
at sun.rmi.server.UnicastRef.invoke(UnicastRef.java:155)
... 9 more

Threads are created in RMI's connection pool with the name 'RMI TCP Connection(idle)'. When one of these is used, the runnable it is being used to execute renames the thread to 'RMI TCP Connection(n)' where n is the connection number being handled (a sequential number), and renames back to 'idle' in the runnable's finally block. So any trace labelled 'RMI TCP Connection(idle)' must come before the runnable renames it as a connection thread, or after it has been renamed back.
Don't ask me how that is possible. The actual answer to your problem, if not your question, is not to modify objects while they are concurrently being returned ;-)

I got to the bottom of it. Problem happens in two cases:
When marshaling a return value throws some exception and that exception in turn contains an object prone to concurrent modification. UnicastServerRef tries to write the cause into the (already corrupted) return stream and causes ConcurrentModificationException.
When method raises an exception and this exception fails to serialize with ConcurrentModificationException (or any other runtime exception).
This exception goes all the way up the stack and is caught and logged by thread pool, not RMI runtime (that's why there is no Exception dispatching call to line at the beginning). That explains thread name being idle since it is already returned to pool from RMI's point of view.
Here's the real exception which is in fact a bit different from what reproduced exception shows in terms of first line and actual call trace:
Exception in thread "RMI TCP Connection(idle)" java.util.ConcurrentModificationException
at java.util.ArrayList.writeObject(ArrayList.java:573)
at sun.reflect.GeneratedMethodAccessor6.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at java.io.ObjectStreamClass.invokeWriteObject(ObjectStreamClass.java:945)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1461)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1392)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1150)
at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1509)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1474)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1392)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1150)
at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1509)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1474)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1392)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1150)
at java.io.ObjectOutputStream.defaultWriteFields(ObjectOutputStream.java:1509)
at java.io.ObjectOutputStream.writeSerialData(ObjectOutputStream.java:1474)
at java.io.ObjectOutputStream.writeOrdinaryObject(ObjectOutputStream.java:1392)
at java.io.ObjectOutputStream.writeObject0(ObjectOutputStream.java:1150)
at java.io.ObjectOutputStream.writeObject(ObjectOutputStream.java:326)
at sun.rmi.server.UnicastServerRef.dispatch(UnicastServerRef.java:343)
at sun.rmi.transport.Transport$1.run(Transport.java:159)
at java.security.AccessController.doPrivileged(Native Method)
at sun.rmi.transport.Transport.serviceCall(Transport.java:155)
at sun.rmi.transport.tcp.TCPTransport.handleMessages(TCPTransport.java:535)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run0(TCPTransport.java:790)
at sun.rmi.transport.tcp.TCPTransport$ConnectionHandler.run(TCPTransport.java:649)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:619)
It doesn't give much clues to the original problem, so I'll have to wait for a client exception to show up at some point to fix that.
If that kind of exception happens when reading JMX attribute by jconsole, it'll not show stacktrace, but will show attribute value as Unavailable.

Axis 2 generated code in "Expanded Mode"

I'm having some problems understanding how to send a request to a web service that I have deployed. I have followed the following tutorial:
http://wso2.org/library/1719
Which I have successfully applied, and it worked well. The tutorial was straightforward, and I have easily generated a web service client. All I did was creating "request" objects from the exposed web service method, set its arguments, and then using the web service stub, I have passed the request object to the exposed web service method, and got a response.
Now, I have received a WSDL file from which I'm supposed to build a web service client as well. The problem is that the generated files from the WSDL differ greatly from that of the tutorial I followed. I learned later on that when generating clients using ADB, there is a mode called "Expanded Mode" that generates " a class for each of the outer elements and the named complex types " (http://axis.apache.org/axis2/java/core/docs/adb/adb-howto.html#gen_modes). The problem is that I'm unable to understand how to create a request object and get a response from the web service from the generated classes. My best shot was as follows:
GetMfrInventoryProductItemsListE wrapper = new GetMfrInventoryProductItemsListE();
GetMfrInventoryProductItemsList request = new GetMfrInventoryProductItemsList();
request.setArg0(deviceId);
request.setArg1(macAddresses);
request.setArg2(mfrKey);
wrapper.setGetMfrInventoryProductItemsList(request);
GetMfrInventoryProductItemsListResponseE wrapperResponse = wmService.getMfrInventoryProductItemsList(wrapper);
GetMfrInventoryProductItemsListResponse response = wrapperResponse.getGetMfrInventoryProductItemsListResponse();
return response.get_return();
In the above code getGetMfrInventoryProductItemsList is the name of my exposed web service method, and wmService is my stub.
The result was the following stack Trace :
org.apache.axis2.AxisFault: Read timed out
at org.apache.axis2.AxisFault.makeFault(AxisFault.java:430)
at org.apache.axis2.transport.http.HTTPSender.sendViaPost(HTTPSender.java:197)
at org.apache.axis2.transport.http.HTTPSender.send(HTTPSender.java:75)
at org.apache.axis2.transport.http.CommonsHTTPTransportSender.writeMessageWithCommons(CommonsHTTPTransportSender.java:404)
at org.apache.axis2.transport.http.CommonsHTTPTransportSender.invoke(CommonsHTTPTransportSender.java:231)
at org.apache.axis2.engine.AxisEngine.send(AxisEngine.java:443)
at org.apache.axis2.description.OutInAxisOperationClient.send(OutInAxisOperation.java:406)
at org.apache.axis2.description.OutInAxisOperationClient.executeImpl(OutInAxisOperation.java:229)
at org.apache.axis2.client.OperationClient.execute(OperationClient.java:165)
at wavemark.wmservice.soap.WMServiceStub.getMfrInventoryProductItemsList(WMServiceStub.java:3275)
at wavemark.linkserver.supplierconnect.controller.WsStub.getMfrInventoryProductItemsList(WsStub.java:107)
at wavemark.linkserver.supplierconnect.controller.WsManager.getProductItems(WsManager.java:384)
at wavemark.linkserver.supplierconnect.webservices.SupplierConnect.getProductItems(SupplierConnect.java:396)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.apache.axis2.rpc.receivers.RPCUtil.invokeServiceClass(RPCUtil.java:212)
at org.apache.axis2.rpc.receivers.RPCMessageReceiver.invokeBusinessLogic(RPCMessageReceiver.java:117)
at org.apache.axis2.receivers.AbstractInOutMessageReceiver.invokeBusinessLogic(AbstractInOutMessageReceiver.java:40)
at org.apache.axis2.receivers.AbstractMessageReceiver.receive(AbstractMessageReceiver.java:110)
at org.apache.axis2.engine.AxisEngine.receive(AxisEngine.java:181)
at org.apache.axis2.transport.http.HTTPTransportUtils.processHTTPPostRequest(HTTPTransportUtils.java:172)
at org.apache.axis2.transport.http.AxisServlet.doPost(AxisServlet.java:146)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:710)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:803)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:230)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:179)
at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:84)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:128)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:104)
at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:156)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:241)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:844)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:580)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
at java.lang.Thread.run(Thread.java:595)
Caused by: java.net.SocketTimeoutException: Read timed out
at java.net.SocketInputStream.socketRead0(Native Method)
at java.net.SocketInputStream.read(SocketInputStream.java:129)
at java.io.BufferedInputStream.fill(BufferedInputStream.java:218)
at java.io.BufferedInputStream.read(BufferedInputStream.java:235)
at org.apache.commons.httpclient.HttpParser.readRawLine(HttpParser.java:78)
at org.apache.commons.httpclient.HttpParser.readLine(HttpParser.java:106)
at org.apache.commons.httpclient.HttpConnection.readLine(HttpConnection.java:1116)
at org.apache.commons.httpclient.MultiThreadedHttpConnectionManager$HttpConnectionAdapter.readLine(MultiThreadedHttpConnectionManager.java:1413)
at org.apache.commons.httpclient.HttpMethodBase.readStatusLine(HttpMethodBase.java:1973)
at org.apache.commons.httpclient.HttpMethodBase.readResponse(HttpMethodBase.java:1735)
at org.apache.commons.httpclient.HttpMethodBase.execute(HttpMethodBase.java:1098)
at org.apache.commons.httpclient.HttpMethodDirector.executeWithRetry(HttpMethodDirector.java:398)
at org.apache.commons.httpclient.HttpMethodDirector.executeMethod(HttpMethodDirector.java:171)
at org.apache.commons.httpclient.HttpClient.executeMethod(HttpClient.java:397)
at org.apache.axis2.transport.http.AbstractHTTPSender.executeMethod(AbstractHTTPSender.java:621)
at org.apache.axis2.transport.http.HTTPSender.sendViaPost(HTTPSender.java:193)
... 42 more
After trying to debug the problem, I have found out that this is the line that is throwing the exception:
GetMfrInventoryProductItemsListResponseE wrapperResponse = wmService.getMfrInventoryProductItemsList(wrapper);
I just want you guys to tell me if the way I'm using the request/response objects is correct.Your help is much appreciated.

Finally, I figured out how to solve the problem. Apparently the web service call that I was making, was taking a lot of time that it was timing out as the stack trace shows. So I added the following to my code to the section where I was instantiating my client stub:
wmService = new WMServiceStub();
Options options = new Options();
EndpointReference epr = new EndpointReference(url);
options.setTo(epr);
options.setProperty(HTTPConstants.SO_TIMEOUT, new Integer(300000));
wmService._getServiceClient().setOptions(options);
This results in increasing the Axis 2 web services' socket timeout to 5 minutes, which should be more than enough to most web service calls. I hope that this will be helpful for some developers out there.