Bproc: java.lang.NullPointerException: element cannot be mapped to a null key

thierry · November 4, 2019, 5:12pm

When trying to show ‘my tasks’.

java.lang.NullPointerException: element cannot be mapped to a null key
	at java.util.Objects.requireNonNull(Objects.java:228)
	at java.util.stream.Collectors.lambda$groupingBy$45(Collectors.java:907)
	at java.util.stream.ReduceOps$3ReducingSink.accept(ReduceOps.java:169)
	at java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1382)
	at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:481)
	at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:471)
	at java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:708)
	at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
	at java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:499)
	at com.haulmont.addon.bproc.web.screens.mytasks.MyTasksBrowse.createTreeItems(MyTasksBrowse.java:181)
	at com.haulmont.addon.bproc.web.screens.mytasks.MyTasksBrowse.createTreeItemsForAssignedTasks(MyTasksBrowse.java:119)
	at com.haulmont.addon.bproc.web.screens.mytasks.MyTasksBrowse.initTasksTree(MyTasksBrowse.java:96)
	at com.haulmont.addon.bproc.web.screens.mytasks.MyTasksBrowse.onBeforeShow(MyTasksBrowse.java:91)
	at com.haulmont.bali.events.EventHub.publish(EventHub.java:170)
	at com.haulmont.cuba.gui.screen.Screen.fireEvent(Screen.java:128)
	at com.haulmont.cuba.gui.screen.UiControllerUtils.fireEvent(UiControllerUtils.java:60)
	at com.haulmont.cuba.web.sys.WebScreens.show(WebScreens.java:435)
	at com.haulmont.cuba.web.sys.WebScreens.showFromNavigation(WebScreens.java:543)
	at com.haulmont.cuba.gui.config.MenuItemCommands$ScreenCommand.run(MenuItemCommands.java:331)
	at com.haulmont.cuba.web.sys.MenuBuilder$MenuCommandExecutor.accept(MenuBuilder.java:256)
	at com.haulmont.cuba.web.sys.MenuBuilder$MenuCommandExecutor.accept(MenuBuilder.java:241)
	at com.haulmont.cuba.web.gui.components.mainwindow.WebAppMenu$MenuItemImpl.menuSelected(WebAppMenu.java:435)
	at com.vaadin.ui.MenuBar.changeVariables(MenuBar.java:225)
	at com.vaadin.server.communication.ServerRpcHandler.changeVariables(ServerRpcHandler.java:611)
	at com.vaadin.server.communication.ServerRpcHandler.handleInvocation(ServerRpcHandler.java:457)
	at com.vaadin.server.communication.ServerRpcHandler.handleInvocations(ServerRpcHandler.java:400)
	at com.vaadin.server.communication.ServerRpcHandler.handleRpc(ServerRpcHandler.java:260)
	at com.vaadin.server.communication.UidlRequestHandler.synchronizedHandleRequest(UidlRequestHandler.java:82)
	at com.vaadin.server.SynchronizedRequestHandler.handleRequest(SynchronizedRequestHandler.java:40)
	at com.vaadin.server.VaadinService.handleRequest(VaadinService.java:1577)
	at com.vaadin.server.VaadinServlet.service(VaadinServlet.java:425)
	at com.haulmont.cuba.web.sys.CubaApplicationServlet.serviceAppRequest(CubaApplicationServlet.java:329)
	at com.haulmont.cuba.web.sys.CubaApplicationServlet.service(CubaApplicationServlet.java:215)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
	at org.springframework.web.filter.CompositeFilter$VirtualFilterChain.doFilter(CompositeFilter.java:107)
	at org.springframework.web.filter.CompositeFilter.doFilter(CompositeFilter.java:73)
	at com.haulmont.cuba.web.sys.CubaHttpFilter.doFilter(CubaHttpFilter.java:93)
	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:199)
	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.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:668)
	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$ConnectionHandler.process(AbstractProtocol.java:834)
	at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1417)
	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)

thierry · November 4, 2019, 5:33pm

Seems like it is because I did not specify a name in (every?) step of the Process Definition. If it is mandatoy, it should not be possible to save the Process definition without the name.

gorbunkov · November 5, 2019, 6:12am

Thank you for you bug reports! If the task doesn’t have a name that should not cause an NPE. We’ll fix this issue, but anyway it’s preferable to have a name for user tasks. At least empty user task model elements looks weird in the process model diagram.

thierry · November 5, 2019, 2:55pm

Hi,

Yes I agree, another option is to make the name mandatory, I leave it up to you to decide what is best?
Is there a way to automatically spot those NPE (with Nullable annotations or the like?)
Thanks
Thierry

gorbunkov · November 5, 2019, 3:10pm

The Flowable engine allows empty task names. Theoretically the process definition can be deployed from the XML file created somewhere else, so I don’t think we should forbid empty task names.

Is there a way to automatically spot those NPE (with Nullable annotations or the like?)

Could you please explain what do you mean?

thierry · November 8, 2019, 1:08am

Indeed good point for the XML import (or is it better to try to generate smtg?)

I was thinking if the properties, methods, arguments … are marked with @Nullable and @NotNull, some tools like https://checkerframework.org or Sonar Cube could spot potential Null Pointers Exceptions (looks like findbugs andle this differently - see The Checker Framework Manual: Custom pluggable types for Java).

Best regards
Thierry