BungeeEx console warning (?)

09:59:40 [WARNING] Plugin performed restricted action, please inform them to use proper API methods: Illegal thread group access
java.security.AccessControlException: Plugin violation: Illegal thread group access
    at net.md_5.bungee.BungeeSecurityManager.checkRestricted(BungeeSecurityManager.java:39)
    at net.md_5.bungee.BungeeSecurityManager.checkAccess(BungeeSecurityManager.java:62)
    at java.lang.ThreadGroup.checkAccess(ThreadGroup.java:315)
    at java.lang.Thread.init(Thread.java:391)
    at java.lang.Thread.init(Thread.java:349)
    at java.lang.Thread.<init>(Thread.java:675)
    at java.lang.UNIXProcess$ProcessReaperThreadFactory.newThread(UNIXProcess.java:160)
    at java.util.concurrent.ThreadPoolExecutor$Worker.<init>(ThreadPoolExecutor.java:610)
    at java.util.concurrent.ThreadPoolExecutor.addWorker(ThreadPoolExecutor.java:924)
    at java.util.concurrent.ThreadPoolExecutor.execute(ThreadPoolExecutor.java:1371)
    at java.lang.UNIXProcess.initStreams(UNIXProcess.java:225)
    at java.lang.UNIXProcess$3.run(UNIXProcess.java:198)
    at java.lang.UNIXProcess$3.run(UNIXProcess.java:196)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.lang.UNIXProcess.<init>(UNIXProcess.java:196)
    at java.lang.ProcessImpl.start(ProcessImpl.java:130)
    at java.lang.ProcessBuilder.start(ProcessBuilder.java:1028)
    at java.lang.Runtime.exec(Runtime.java:617)
    at java.lang.Runtime.exec(Runtime.java:450)
    at com.comze_instancelabs.executeshbungee.Main.startServer(Main.java:88)
    at com.comze_instancelabs.executeshbungee.Main$4.run(Main.java:51)
    at net.md_5.bungee.scheduler.BungeeTask.run(BungeeTask.java:58)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:745)