<timer-service thread-pool-name="default" default-data-store="store">
                <data-stores>
                    <database-data-store name="store" database="oracle" datasource-jndi-name="java:jboss/datasources/ExampleDS" partition="ejb_timer_part" refresh-interval="30000"/>
                </data-stores>
            </timer-service> 

10:55:20,905 ERROR [org.jboss.msc.service.fail] (MSC service thread 1-8) MSC000001: Failed to start service org.wildfly.ejb3.timer-service.timer-persistence-service.store: org.jboss.msc.service.StartException in service org.wildfly.ejb3.timer-service.timer-persistence-service.store: Failed to start service
at org.jboss.msc.service.ServiceControllerImpl$StartTask.execute(ServiceControllerImpl.java:1731)
at org.jboss.msc.service.ServiceControllerImpl$ControllerTask.run(ServiceControllerImpl.java:1559)
at org.jboss.threads.ContextClassLoaderSavingRunnable.run(ContextClassLoaderSavingRunnable.java:35)
at org.jboss.threads.EnhancedQueueExecutor.safeRun(EnhancedQueueExecutor.java:1990)
at org.jboss.threads.EnhancedQueueExecutor$ThreadBody.doRunTask(EnhancedQueueExecutor.java:1486)
at org.jboss.threads.EnhancedQueueExecutor$ThreadBody.run(EnhancedQueueExecutor.java:1377)
at java.lang.Thread.run(Thread.java:750)
Caused by: java.lang.NullPointerException
at org.jboss.as.ejb3.timerservice.persistence.database.DatabaseTimerPersistence.adjustCreateAutoTimerStatement(DatabaseTimerPersistence.java:323)
at org.jboss.as.ejb3.timerservice.persistence.database.DatabaseTimerPersistence.identifyDialect(DatabaseTimerPersistence.java:311)
at org.jboss.as.ejb3.timerservice.persistence.database.DatabaseTimerPersistence.investigateDialect(DatabaseTimerPersistence.java:280)
at org.jboss.as.ejb3.timerservice.persistence.database.DatabaseTimerPersistence.start(DatabaseTimerPersistence.java:187)
at org.jboss.msc.service.ServiceControllerImpl$StartTask.startService(ServiceControllerImpl.java:1739)
at org.jboss.msc.service.ServiceControllerImpl$StartTask.execute(ServiceControllerImpl.java:1701)
... 6 more