OptaPlanner on KIE Server running on Wildfly 9.0.2 throwing IllegalArgumentException on startup

The following exception is thrown at startup. The server still starts successfully.

[31m04:08:44,729 ERROR [org.kie.server.services.impl.KieServerImpl] (ServerService Thread Pool – 65) Error when initializing server extension of type OptaPlanner KIE Server extension: java.lang.IllegalArgumentException
at java.util.concurrent.ThreadPoolExecutor.<init>(ThreadPoolExecutor.java:1307)
at java.util.concurrent.ThreadPoolExecutor.<init>(ThreadPoolExecutor.java:1195)
at org.kie.server.services.optaplanner.OptaplannerKieServerExtension.init(OptaplannerKieServerExtension.java:75)
at org.kie.server.services.impl.KieServerImpl.<init>(KieServerImpl.java:108)
at org.kie.server.services.impl.KieServerLocator.<clinit>(KieServerLocator.java:20)
at org.kie.server.services.Bootstrap.contextInitialized(Bootstrap.java:50)
at io.undertow.servlet.core.ApplicationListeners.contextInitialized(ApplicationListeners.java:173)
at io.undertow.servlet.core.DeploymentManagerImpl.deploy(DeploymentManagerImpl.java:195)
at org.wildfly.extension.undertow.deployment.UndertowDeploymentService.startContext(UndertowDeploymentService.java:100)
at org.wildfly.extension.undertow.deployment.UndertowDeploymentService$1.run(UndertowDeploymentService.java:82)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511)
at java.util.concurrent.FutureTask.run(FutureTask.java:266)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
at java.lang.Thread.run(Thread.java:745)
at org.jboss.threads.JBossThread.run(JBossThread.java:320)