java.lang.NullPointerException
   at com.nazca.io.httpdao.HttpClientContextManager.getContext(HttpClientContextManager.java:24)
   at com.nazca.io.httprpc.HttpRPC$RPCInvokeHandler.invoke(HttpRPC.java:163)
   at $Proxy25.getCreditMaterialsByType(.java:0)
   at com.renrendai.client.agents.GetCreditMaterialsAgent.doExecute(GetCreditMaterialsAgent.java:29)
   at com.renrendai.client.agents.GetCreditMaterialsAgent.doExecute(GetCreditMaterialsAgent.java:19)
   at com.renrendai.client.agents.AbstractAgent$1.doInBackground(AbstractAgent.java:53)
   at javax.swing.SwingWorker$1.call(SwingWorker.java:277)
   at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
   at java.util.concurrent.FutureTask.run(FutureTask.java:138)
   at javax.swing.SwingWorker.run(SwingWorker.java:316)
   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:637)