In the freemarker-based templating mechanism for task forms, 'outcome' is both
"a default context information for templates".
and
"reserved field name for signaling execution".

Additionaly, "form field names become process variables and vice-versa".

(See http://www.jboss.org/index.html?module=bb&op=viewtopic&t=155048.)

,-- example code in the documentation –

This code works exactly once.
If used a second time, outcome will have become a process variable and therefore the result is an exception like:

2009-07-23 15:18:44,485 ERROR [freemarker.runtime] (http-127.0.0.1-8080-4)
Expected hash. outcome evaluated instead to freemarker.template.SimpleScalar on line 5, column 32 in review.ftl.
The problematic instruction:
----------
==> list outcome.values as transition [on line 5, column 25 in review.ftl]
----------
Java backtrace for programmers:
----------
freemarker.template.TemplateException: Expected hash. outcome evaluated instead to freemarker.template.SimpleScalar on line 5, column 32 in review.ftl.
at freemarker.core.TemplateObject.invalidTypeException(TemplateObject.java:135)
at freemarker.core.Dot._getAsTemplateModel(Dot.java:78)
at freemarker.core.Expression.getAsTemplateModel(Expression.java:89)
at freemarker.core.IteratorBlock.accept(IteratorBlock.java:94)
at freemarker.core.Environment.visit(Environment.java:209)
at freemarker.core.MixedContent.accept(MixedContent.java:92)
at freemarker.core.Environment.visit(Environment.java:209)
at freemarker.core.Environment.process(Environment.java:189)
at freemarker.template.Template.process(Template.java:237)
at org.jbpm.integration.console.forms.AbstractFormDispatcher.processTemplate(AbstractFormDispatcher.java:116)
at org.jbpm.integration.console.forms.TaskFormDispatcher.provideForm(TaskFormDispatcher.java:161)
at org.jbpm.integration.console.forms.FormDispatcherComposite.provideForm(FormDispatcherComposite.java:65)
at sun.reflect.GeneratedMethodAccessor312.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.jboss.bpm.console.server.util.InvocationProxy.invoke(InvocationProxy.java:64)
at $Proxy291.provideForm(Unknown Source)
at org.jboss.bpm.console.server.FormProcessingFacade.provideForm(FormProcessingFacade.java:181)
at org.jboss.bpm.console.server.FormProcessingFacade.renderTaskUI(FormProcessingFacade.java:120)
at sun.reflect.GeneratedMethodAccessor311.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.jboss.resteasy.core.MethodInjectorImpl.invoke(MethodInjectorImpl.java:117)
at org.jboss.resteasy.core.ResourceMethod.invokeOnTarget(ResourceMethod.java:260)
at org.jboss.resteasy.core.ResourceMethod.invoke(ResourceMethod.java:232)
at org.jboss.resteasy.core.ResourceMethod.invoke(ResourceMethod.java:166)
at org.jboss.resteasy.core.DispatcherUtilities.getJaxrsResponse(DispatcherUtilities.java:142)
at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:356)
at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:173)
at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:93)
at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:68)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.jboss.bpm.console.server.util.GWTJsonFilter.doFilter(GWTJsonFilter.java:59)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:235)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:190)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:433)
at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:92)
at org.jboss.web.tomcat.security.SecurityContextEstablishmentValve.process(SecurityContextEstablishmentValve.java:126)
at org.jboss.web.tomcat.security.SecurityContextEstablishmentValve.invoke(SecurityContextEstablishmentValve.java:70)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:158)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:330)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:829)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:598)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
at java.lang.Thread.run(Thread.java:619)
2009-07-23 15:18:44,485 ERROR [org.apache.catalina.core.ContainerBase.[jboss.web].[localhost].[/gwt-console-server].[Resteasy]] (http-127.0.0.1-8080-4) Servlet.service() for servlet Resteasy threw exception
org.jboss.resteasy.spi.UnhandledException: java.lang.RuntimeException: Unexpected invocation exception: null
at org.jboss.resteasy.core.SynchronousDispatcher.handleApplicationException(SynchronousDispatcher.java:319)
at org.jboss.resteasy.core.SynchronousDispatcher.handleException(SynchronousDispatcher.java:230)
at org.jboss.resteasy.core.SynchronousDispatcher.handleInvokerException(SynchronousDispatcher.java:206)
at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:360)
at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:173)
at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:93)
at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:68)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.jboss.bpm.console.server.util.GWTJsonFilter.doFilter(GWTJsonFilter.java:59)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:235)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:190)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:433)
at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:92)
at org.jboss.web.tomcat.security.SecurityContextEstablishmentValve.process(SecurityContextEstablishmentValve.java:126)
at org.jboss.web.tomcat.security.SecurityContextEstablishmentValve.invoke(SecurityContextEstablishmentValve.java:70)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:158)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:330)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:829)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:598)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
at java.lang.Thread.run(Thread.java:619)
Caused by: java.lang.RuntimeException: Unexpected invocation exception: null
at org.jboss.bpm.console.server.util.InvocationProxy.invoke(InvocationProxy.java:80)
at $Proxy291.provideForm(Unknown Source)
at org.jboss.bpm.console.server.FormProcessingFacade.provideForm(FormProcessingFacade.java:181)
at org.jboss.bpm.console.server.FormProcessingFacade.renderTaskUI(FormProcessingFacade.java:120)
at sun.reflect.GeneratedMethodAccessor311.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.jboss.resteasy.core.MethodInjectorImpl.invoke(MethodInjectorImpl.java:117)
at org.jboss.resteasy.core.ResourceMethod.invokeOnTarget(ResourceMethod.java:260)
at org.jboss.resteasy.core.ResourceMethod.invoke(ResourceMethod.java:232)
at org.jboss.resteasy.core.ResourceMethod.invoke(ResourceMethod.java:166)
at org.jboss.resteasy.core.DispatcherUtilities.getJaxrsResponse(DispatcherUtilities.java:142)
at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:356)
... 28 more
Caused by: java.lang.reflect.InvocationTargetException
at sun.reflect.GeneratedMethodAccessor312.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.jboss.bpm.console.server.util.InvocationProxy.invoke(InvocationProxy.java:64)
... 40 more
Caused by: java.lang.RuntimeException: Failed to process task template
at org.jbpm.integration.console.forms.AbstractFormDispatcher.processTemplate(AbstractFormDispatcher.java:149)
at org.jbpm.integration.console.forms.TaskFormDispatcher.provideForm(TaskFormDispatcher.java:161)
at org.jbpm.integration.console.forms.FormDispatcherComposite.provideForm(FormDispatcherComposite.java:65)
... 44 more
Caused by: freemarker.template.TemplateException: Expected hash. outcome evaluated instead to freemarker.template.SimpleScalar on line 5, column 32 in review.ftl.
at freemarker.core.TemplateObject.invalidTypeException(TemplateObject.java:135)
at freemarker.core.Dot._getAsTemplateModel(Dot.java:78)
at freemarker.core.Expression.getAsTemplateModel(Expression.java:89)
at freemarker.core.IteratorBlock.accept(IteratorBlock.java:94)
at freemarker.core.Environment.visit(Environment.java:209)
at freemarker.core.MixedContent.accept(MixedContent.java:92)
at freemarker.core.Environment.visit(Environment.java:209)
at freemarker.core.Environment.process(Environment.java:189)
at freemarker.template.Template.process(Template.java:237)
at org.jbpm.integration.console.forms.AbstractFormDispatcher.processTemplate(AbstractFormDispatcher.java:116)
... 46 more