{"action":"opened","issue":{"url":"https://api.github.com/repos/tuanhiep/mqtt-jmeter/issues/13","labels_url":"https://api.github.com/repos/tuanhiep/mqtt-jmeter/issues/13/labels{/name}","comments_url":"https://api.github.com/repos/tuanhiep/mqtt-jmeter/issues/13/comments","events_url":"https://api.github.com/repos/tuanhiep/mqtt-jmeter/issues/13/events","html_url":"https://github.com/tuanhiep/mqtt-jmeter/issues/13","id":88039076,"number":13,"title":"getting NullPointerException error","user":{"login":"andreibosco","id":607297,"avatar_url":"https://avatars.githubusercontent.com/u/607297?v=3","gravatar_id":"","url":"https://api.github.com/users/andreibosco","html_url":"https://github.com/andreibosco","followers_url":"https://api.github.com/users/andreibosco/followers","following_url":"https://api.github.com/users/andreibosco/following{/other_user}","gists_url":"https://api.github.com/users/andreibosco/gists{/gist_id}","starred_url":"https://api.github.com/users/andreibosco/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/andreibosco/subscriptions","organizations_url":"https://api.github.com/users/andreibosco/orgs","repos_url":"https://api.github.com/users/andreibosco/repos","events_url":"https://api.github.com/users/andreibosco/events{/privacy}","received_events_url":"https://api.github.com/users/andreibosco/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":0,"created_at":"2015-06-13T17:36:53Z","updated_at":"2015-06-13T17:36:53Z","closed_at":null,"body":"I'm getting the following error when I try to make an MQTT test (either pub or sub):\r\n`2015/06/13 14:26:27 ERROR - jmeter.protocol.java.sampler.AbstractJavaSamplerClient:`\r\n\r\nAnd when I stop the simulation the following error message is shown in the log:\r\n```\r\n2015/06/13 14:29:17 ERROR - jmeter.JMeter: Uncaught exception:  java.lang.NullPointerException\r\n\tat org.fusesource.mqtt.client.CallbackConnection$8.onSuccess(CallbackConnection.java:506)\r\n\tat org.fusesource.mqtt.client.CallbackConnection$8.onSuccess(CallbackConnection.java:495)\r\n\tat org.fusesource.mqtt.client.CallbackConnection.disconnect(CallbackConnection.java:519)\r\n\tat org.fusesource.mqtt.client.FutureConnection$3.run(FutureConnection.java:104)\r\n\tat org.fusesource.hawtdispatch.internal.SerialDispatchQueue.run(SerialDispatchQueue.java:96)\r\n\tat org.fusesource.hawtdispatch.internal.pool.SimpleThread.run(SimpleThread.java:77)\r\n```\r\nHere's a screenshot of the parameters I'm using in Jmeter: https://dl.dropboxusercontent.com/u/546167/jmeter-mqtt-error.PNG"}}