Description of problem:

First time open a Process in designer, you can see error "11:26:46,822 ERROR [org.jbpm.designer.web.server.DictionaryServlet] (http-/127.0.0.1:8080-2) null" appears in server.log.

Version-Release number of selected component (if applicable):

How reproducible:

Steps to Reproduce:
1. Add a user by ./add-user.sh and login
2. Click the "Process Authoring"
3. Click "Prssoce" in left bar and Click "hiring" . You can see the error appears in server.log

Actual results:

Expected results:

Additional info:
Part of server.log：
11:26:41,013 INFO [org.jbpm.designer.server.EditorHandler] (http-/127.0.0.1:8080-3) The diagram editor is running in development mode. Javascript will be served uncompressed
11:26:41,015 INFO [org.jbpm.designer.server.EditorHandler] (http-/127.0.0.1:8080-3) Performing diagram information pre-processing steps.
11:26:41,592 INFO [org.jbpm.designer.web.preprocessing.impl.JbpmPreprocessingUnit] (http-/127.0.0.1:8080-3) Successfully deleted file :/tmp/July10/jboss-eap-6.1/standalone/deployments/business-central.war/org.kie.workbench.KIEWebapp/stencilsets/bpmn2.0jbpm/bpmn2.0jbpm.json
11:26:41,641 INFO [org.jbpm.designer.web.preprocessing.impl.JbpmPreprocessingUnit] (http-/127.0.0.1:8080-3) Created file:/tmp/July10/jboss-eap-6.1/standalone/deployments/business-central.war/org.kie.workbench.KIEWebapp/stencilsets/bpmn2.0jbpm/bpmn2.0jbpm.json
11:26:41,664 INFO [org.jbpm.designer.web.preprocessing.impl.JbpmPreprocessingUnit] (http-/127.0.0.1:8080-3) Created file:/tmp/July10/jboss-eap-6.1/standalone/deployments/business-central.war/org.kie.workbench.KIEWebapp/stencilsets/bpmn2.0jbpm/view/activity/workitems/Log.svg
11:26:41,674 INFO [org.jbpm.designer.web.preprocessing.impl.JbpmPreprocessingUnit] (http-/127.0.0.1:8080-3) Created file:/tmp/July10/jboss-eap-6.1/standalone/deployments/business-central.war/org.kie.workbench.KIEWebapp/stencilsets/bpmn2.0jbpm/view/activity/workitems/Email.svg
11:26:41,694 INFO [org.jbpm.designer.server.EditorHandler] (http-/127.0.0.1:8080-3) Performing diagram information pre-processing steps.
11:26:41,924 INFO [org.jbpm.designer.web.preprocessing.impl.JbpmPreprocessingUnit] (http-/127.0.0.1:8080-3) Successfully deleted file :/tmp/July10/jboss-eap-6.1/standalone/deployments/business-central.war/org.kie.workbench.KIEWebapp/stencilsets/bpmn2.0jbpm/bpmn2.0jbpm.json
11:26:41,936 INFO [org.jbpm.designer.web.preprocessing.impl.JbpmPreprocessingUnit] (http-/127.0.0.1:8080-3) Created file:/tmp/July10/jboss-eap-6.1/standalone/deployments/business-central.war/org.kie.workbench.KIEWebapp/stencilsets/bpmn2.0jbpm/bpmn2.0jbpm.json
11:26:41,936 INFO [org.jbpm.designer.web.preprocessing.impl.JbpmPreprocessingUnit] (http-/127.0.0.1:8080-3) Successfully deleted file :/tmp/July10/jboss-eap-6.1/standalone/deployments/business-central.war/org.kie.workbench.KIEWebapp/stencilsets/bpmn2.0jbpm/view/activity/workitems/Email.svg
11:26:41,936 INFO [org.jbpm.designer.web.preprocessing.impl.JbpmPreprocessingUnit] (http-/127.0.0.1:8080-3) Successfully deleted file :/tmp/July10/jboss-eap-6.1/standalone/deployments/business-central.war/org.kie.workbench.KIEWebapp/stencilsets/bpmn2.0jbpm/view/activity/workitems/Log.svg
11:26:41,946 INFO [org.jbpm.designer.web.preprocessing.impl.JbpmPreprocessingUnit] (http-/127.0.0.1:8080-3) Created file:/tmp/July10/jboss-eap-6.1/standalone/deployments/business-central.war/org.kie.workbench.KIEWebapp/stencilsets/bpmn2.0jbpm/view/activity/workitems/Log.svg
11:26:41,955 INFO [org.jbpm.designer.web.preprocessing.impl.JbpmPreprocessingUnit] (http-/127.0.0.1:8080-3) Created file:/tmp/July10/jboss-eap-6.1/standalone/deployments/business-central.war/org.kie.workbench.KIEWebapp/stencilsets/bpmn2.0jbpm/view/activity/workitems/Email.svg
11:26:46,822 ERROR [org.jbpm.designer.web.server.DictionaryServlet] (http-/127.0.0.1:8080-2) null