org.jboss.as.connector.services.workmanager.StatisticsExecutorImpl tests the type of the Executor impl it is provided in order to cast to the concrete type and invoke getters on it. Included in its checks are ones for org.jboss.threads.JBossThreadPoolExecutor org.jboss.threads.management.ThreadPoolExecutorMBean, neither of which exist in JBoss Threads 3.9. So, this code prevents us from moving from JBoss Threads 2.4 to 3.9 (WFCORE-7045).

Even with our JBoss Threads 2.4 integration, the Executor type that will be injected won't be either of these types, so this code can be removed.