I ran a similar tests described in this thread:

https://groups.google.com/forum/?fromgroups#!topic/camunda-bpm-users/QaIiLT8MKF4

This time the Service Task is not bound to a fixed class name, but using EL. Unfortunately, when I signal the failed service task I get a cannot resolve identifier error - see below. I first ran the process using beans that have no errors and it was successful, so the resolution was working for the happy path.

This is related to the bug CAM-1371, but the main difference is that the Class ServiceTaskDelegateExpressionActivityBehavior is not using ClassDelegate, unlike ServiceTaskJavaDelegateActivityBehavior.

The fix should include an integration testcase in qa/integration-tests-engine

Stack trace:
at org.camunda.bpm.engine.impl.el.JuelExpression.getValue(JuelExpression.java:55)
at org.camunda.bpm.engine.impl.bpmn.behavior.ServiceTaskDelegateExpressionActivityBehavior.signal(ServiceTaskDelegateExpressionActivityBehavior.java:53)
at org.camunda.bpm.engine.impl.persistence.entity.ExecutionEntity.signal(ExecutionEntity.java:429)
at org.camunda.bpm.engine.impl.cmd.SignalCmd.execute(SignalCmd.java:71)
at org.camunda.bpm.engine.impl.interceptor.CommandExecutorImpl.execute(CommandExecutorImpl.java:24)
at org.camunda.bpm.engine.impl.interceptor.CommandContextInterceptor.execute(CommandContextInterceptor.java:42)
at org.camunda.bpm.engine.impl.interceptor.JtaTransactionInterceptor.execute(JtaTransactionInterceptor.java:59)
at org.camunda.bpm.engine.impl.interceptor.LogInterceptor.execute(LogInterceptor.java:32)
at org.camunda.bpm.engine.impl.RuntimeServiceImpl.signal(RuntimeServiceImpl.java:202)
at org.camunda.bpm.engine.rest.sub.runtime.impl.ExecutionResourceImpl.signalExecution(ExecutionResourceImpl.java:72)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.jboss.resteasy.core.MethodInjectorImpl.invoke(MethodInjectorImpl.java:167)
at org.jboss.resteasy.core.ResourceMethod.invokeOnTarget(ResourceMethod.java:257)
at org.jboss.resteasy.core.ResourceMethod.invoke(ResourceMethod.java:222)
at org.jboss.resteasy.core.ResourceLocator.invokeOnTargetObject(ResourceLocator.java:159)
at org.jboss.resteasy.core.ResourceLocator.invoke(ResourceLocator.java:92)
at org.jboss.resteasy.core.SynchronousDispatcher.getResponse(SynchronousDispatcher.java:542)
at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:524)
at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:126)
at org.jboss.resteasy.plugins.server.servlet.ServletContainerDispatcher.service(ServletContainerDispatcher.java:208)
at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:55)
at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:50)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:295)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:214)
at org.camunda.bpm.engine.rest.filter.CacheControlFilter.doFilter(CacheControlFilter.java:47)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:246)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:214)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:230)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:149)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:481)
at org.jboss.as.web.security.SecurityContextAssociationValve.invoke(SecurityContextAssociationValve.java:169)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:145)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:97)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:102)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:336)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:856)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:653)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:920)
at java.lang.Thread.run(Thread.java:744)
Caused by: org.camunda.bpm.engine.impl.javax.el.PropertyNotFoundException: Cannot resolve identifier 'simpleFailedBean'
at org.camunda.bpm.engine.impl.juel.AstIdentifier.eval(AstIdentifier.java:83)
at org.camunda.bpm.engine.impl.juel.AstEval.eval(AstEval.java:50)
at org.camunda.bpm.engine.impl.juel.AstNode.getValue(AstNode.java:26)
at org.camunda.bpm.engine.impl.juel.TreeValueExpression.getValue(TreeValueExpression.java:114)
at org.camunda.bpm.engine.impl.delegate.ExpressionGetInvocation.invoke(ExpressionGetInvocation.java:33)
at org.camunda.bpm.engine.impl.delegate.DelegateInvocation.proceed(DelegateInvocation.java:39)
at org.camunda.bpm.engine.impl.delegate.DefaultDelegateInterceptor.handleInvocation(DefaultDelegateInterceptor.java:42)
at org.camunda.bpm.engine.impl.el.JuelExpression.getValue(JuelExpression.java:50)
... 42 more