RS in access control administration

<dispatchinfo>
	<componentinfo>
		<compname>ffo_main_null</compname>
		<compclass>org.olat.core.gui.components.form.flexible.impl.FormWrapperContainer</compclass>
		<extendedinfo>n/a</extendedinfo>
		<event>
			<class&gt;org.olat.core.gui.control.Event</class&gt;
			<command>validation ok</command>
			<tostring>com:validation ok,org.olat.core.gui.control.Event@d62b3f02</tostring>
		</event>
	</componentinfo>
	<controllerinfo>
		<controllername>org.olat.resource.accesscontrol.ui.AccessControlAdminController</controllername>
		<controllername>org.olat.admin.SystemAdminMainController</controllername>
		<controllername>org.olat.core.commons.fullWebApp.BaseFullWebappController</controllername>
	</controllerinfo>
</dispatchinfo> 

Throwable: javax.persistence.PersistenceException
message:org.hibernate.PropertyValueException: not-null property references a null or transient value : org.olat.resource.accesscontrol.model.FreeAccessMethod.lastModified,javax.persistence.PersistenceException
  at org.hibernate.jpa.spi.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1763)
  at org.hibernate.jpa.spi.AbstractEntityManagerImpl.convert(AbstractEntityManagerImpl.java:1677)
  at org.hibernate.jpa.internal.QueryImpl.getResultList(QueryImpl.java:458)
  at org.olat.resource.accesscontrol.manager.ACMethodDAO.enableMethod(ACMethodDAO.java:108)
  at org.olat.resource.accesscontrol.AccessControlModule.setTokenEnabled(AccessControlModule.java:167)
  at org.olat.resource.accesscontrol.ui.AccessControlAdminController.formOK(AccessControlAdminController.java:143)
  at org.olat.core.gui.components.form.flexible.impl.FormBasicController.event(FormBasicController.java:380)
  at org.olat.core.gui.control.DefaultController.dispatchEvent(DefaultController.java:202)
  at org.olat.core.gui.components.AbstractComponent$1.run(AbstractComponent.java:240)
  at org.olat.core.logging.activity.ThreadLocalUserActivityLoggerInstaller.runWithUserActivityLogger(ThreadLocalUserActivityLoggerInstaller.java:108)

1. cause:
message:not-null property references a null or transient value : org.olat.resource.accesscontrol.model.FreeAccessMethod.lastModified,org.hibernate.PropertyValueException
  at org.hibernate.engine.internal.Nullability.checkNullability(Nullability.java:106)
  at org.hibernate.event.internal.DefaultFlushEntityEventListener.scheduleUpdate(DefaultFlushEntityEventListener.java:309)
  at org.hibernate.event.internal.DefaultFlushEntityEventListener.onFlushEntity(DefaultFlushEntityEventListener.java:160)
  at org.hibernate.event.internal.AbstractFlushingEventListener.flushEntities(AbstractFlushingEventListener.java:231)
  at org.hibernate.event.internal.AbstractFlushingEventListener.flushEverythingToExecutions(AbstractFlushingEventListener.java:102)
  at org.hibernate.event.internal.DefaultAutoFlushEventListener.onAutoFlush(DefaultAutoFlushEventListener.java:61)
  at org.hibernate.internal.SessionImpl.autoFlushIfRequired(SessionImpl.java:1227)
  at org.hibernate.internal.SessionImpl.list(SessionImpl.java:1293)
  at org.hibernate.internal.QueryImpl.list(QueryImpl.java:103)
  at org.hibernate.jpa.internal.QueryImpl.list(QueryImpl.java:573)