Concurrency issue in strust2 app deployed in JBoss AS7

ERROR [org.apache.catalina.core.ContainerBase.[jboss.web].[default-host].[/pgr]] (ServerService Thread Pool -- 50) JBWEB000284: Exception starting filter struts2Prepare: Class: org.apache.struts2.config.LegacyPropertiesConfigurationProvider
File: LegacyPropertiesConfigurationProvider.java
Method: loadSettings
Line: 108 - org/apache/struts2/config/LegacyPropertiesConfigurationProvider.java:108:-1
	at org.apache.struts2.dispatcher.Dispatcher.init(Dispatcher.java:502) [struts2-core-2.3.15.jar:2.3.15]
	at org.apache.struts2.dispatcher.ng.InitOperations.initDispatcher(InitOperations.java:74) [struts2-core-2.3.15.jar:2.3.15]
	at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareFilter.init(StrutsPrepareFilter.java:56) [struts2-core-2.3.15.jar:2.3.15]
	at org.apache.catalina.core.ApplicationFilterConfig.getFilter(ApplicationFilterConfig.java:416) [jbossweb-7.2.0.Final-redhat-1.jar:7.2.0.Final-redhat-1]
	at org.apache.catalina.core.StandardContext.filterStart(StandardContext.java:3225) [jbossweb-7.2.0.Final-redhat-1.jar:7.2.0.Final-redhat-1]
	at org.apache.catalina.core.StandardContext.start(StandardContext.java:3791) [jbossweb-7.2.0.Final-redhat-1.jar:7.2.0.Final-redhat-1]
	at org.jboss.as.web.deployment.WebDeploymentService.doStart(WebDeploymentService.java:156) [jboss-as-web-7.2.0.Final-redhat-8.jar:7.2.0.Final-redhat-8]
	at org.jboss.as.web.deployment.WebDeploymentService.access$000(WebDeploymentService.java:60) [jboss-as-web-7.2.0.Final-redhat-8.jar:7.2.0.Final-redhat-8]
	at org.jboss.as.web.deployment.WebDeploymentService$1.run(WebDeploymentService.java:93) [jboss-as-web-7.2.0.Final-redhat-8.jar:7.2.0.Final-redhat-8]
	at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:471) [rt.jar:1.7.0_25]
	at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334) [rt.jar:1.7.0_25]
	at java.util.concurrent.FutureTask.run(FutureTask.java:166) [rt.jar:1.7.0_25]
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145) [rt.jar:1.7.0_25]
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615) [rt.jar:1.7.0_25]
	at java.lang.Thread.run(Thread.java:724) [rt.jar:1.7.0_25]
	at org.jboss.threads.JBossThread.run(JBossThread.java:122)
Caused by: java.lang.NullPointerException
	at org.apache.struts2.config.LegacyPropertiesConfigurationProvider.loadSettings(LegacyPropertiesConfigurationProvider.java:108) [struts2-core-2.3.15.jar:2.3.15]
	at org.apache.struts2.config.LegacyPropertiesConfigurationProvider.register(LegacyPropertiesConfigurationProvider.java:68) [struts2-core-2.3.15.jar:2.3.15]
	at com.opensymphony.xwork2.config.impl.DefaultConfiguration.reloadContainer(DefaultConfiguration.java:226) [xwork-core-2.3.15.jar:2.3.15]
	at com.opensymphony.xwork2.config.ConfigurationManager.getConfiguration(ConfigurationManager.java:67) [xwork-core-2.3.15.jar:2.3.15]
	at org.apache.struts2.dispatcher.Dispatcher.init_PreloadConfiguration(Dispatcher.java:446) [struts2-core-2.3.15.jar:2.3.15]
	at org.apache.struts2.dispatcher.Dispatcher.init(Dispatcher.java:490) [struts2-core-2.3.15.jar:2.3.15]
	... 15 more