org.sakaiproject.datemanager.impl.DateManagerServiceImpl.validateLessons Error trying to validate Lessons {}

java.lang.NullPointerException: dueDate is marked non-null but is null

	at org.sakaiproject.datemanager.api.model.DateManagerUpdate.<init>(DateManagerUpdate.java:23)

	at org.sakaiproject.datemanager.impl.DateManagerServiceImpl.validateLessons(DateManagerServiceImpl.java:1376)

	at org.sakaiproject.datemanager.tool.MainController.dateManagerUpdate(MainController.java:169)

	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)

	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)

	at java.lang.reflect.Method.invoke(Method.java:498)

	at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:190)

	at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138)

	at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:105)

	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:878)

	at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:792)

	at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)

	at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1040)

	at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:943)

	at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1006)

	at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:909)

	at javax.servlet.http.HttpServlet.service(HttpServlet.java:660)

	at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:883)

	at javax.servlet.http.HttpServlet.service(HttpServlet.java:741)

	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)

	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)

	at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:712)

	at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:459)

	at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:352)

	at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:312)

	at org.sakaiproject.tool.impl.ActiveToolComponent$MyActiveTool.help(ActiveToolComponent.java:578)

	at org.sakaiproject.cheftool.ToolServlet.sendToHelper(ToolServlet.java:675)

	at org.sakaiproject.cheftool.ToolServlet.doGet(ToolServlet.java:219)

	at org.sakaiproject.cheftool.VelocityPortletPaneledAction.doGet(VelocityPortletPaneledAction.java:1081)

	at org.sakaiproject.cheftool.ToolServlet.doPost(ToolServlet.java:152)

	at javax.servlet.http.HttpServlet.service(HttpServlet.java:660)

	at org.sakaiproject.vm.ComponentServlet.service(ComponentServlet.java:56)

	at javax.servlet.http.HttpServlet.service(HttpServlet.java:741)

	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)

	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)

	at org.sakaiproject.util.RequestFilter.doFilter(RequestFilter.java:447)

	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)

	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)

	at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:712)

	at org.apache.catalina.core.ApplicationDispatcher.processRequest(ApplicationDispatcher.java:459)

	at org.apache.catalina.core.ApplicationDispatcher.doForward(ApplicationDispatcher.java:352)

	at org.apache.catalina.core.ApplicationDispatcher.forward(ApplicationDispatcher.java:312)

	at org.sakaiproject.tool.impl.ActiveToolComponent$MyActiveTool.forward(ActiveToolComponent.java:508)

	at org.sakaiproject.portal.charon.SkinnableCharonPortal.forwardTool(SkinnableCharonPortal.java:1502)

	at org.sakaiproject.portal.charon.handlers.SiteHandler.doToolBuffer(SiteHandler.java:1254)

	at org.sakaiproject.portal.charon.handlers.SiteHandler.bufferContent(SiteHandler.java:1088)

	at org.sakaiproject.portal.charon.handlers.SiteHandler.doSite(SiteHandler.java:499)

	at org.sakaiproject.portal.charon.handlers.SiteHandler.doGet(SiteHandler.java:275)

	at org.sakaiproject.portal.charon.handlers.SiteHandler.doGet(SiteHandler.java:163)

	at org.sakaiproject.portal.charon.handlers.WorksiteHandler.doPost(WorksiteHandler.java:69)

	at org.sakaiproject.portal.charon.SkinnableCharonPortal.doPost(SkinnableCharonPortal.java:1175)

	at javax.servlet.http.HttpServlet.service(HttpServlet.java:660)

	at javax.servlet.http.HttpServlet.service(HttpServlet.java:741)

	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)

	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)

	at org.sakaiproject.util.RequestFilter.doFilter(RequestFilter.java:496)

	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)

	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)

	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)

	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)

	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)

	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:200)

	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)

	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:490)

	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139)

	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)

	at org.apache.catalina.valves.RemoteIpValve.invoke(RemoteIpValve.java:679)

	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)

	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)

	at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:408)

	at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)

	at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:836)

	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1747)

	at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)

	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)

	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)

	at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)

	at java.lang.Thread.run(Thread.java:748)