title: Apache Camel multicast, exception and Aggregation strategy
body: <p>I define a complex route in which I had to to orchestrate different simple operations.</p>
  
  <pre><code>   from(cxfCartEndpoint).routeId("receiveCart")
      .to("log:com.sdmo.input?level="+LOG_LEVEL)
      .process(cartWSExtractProcessor)
      .to(loggingMesssagesPath+"?fileName=originalRequest${date:now:yyyyMMdd-HHmmss}.xml")
      .multicast(aggregationStrategy).stopOnException()
         .to("mock:doNothing","direct:copyItem","direct:XmlSave","direct:manageFinalResponse")
          .end()
       .to(loggingMesssagesPath+"?fileName=finalResponse${date:now:yyyyMMdd-HHmmss}.xml")
       .process(new ConvertCartResponseProcessor())
       .to("log:com.sdmo.output?level="+LOG_LEVEL)
       ;
  </code></pre>
  
  <p>The from endpoint is a cxf WS in POJO mode, and I need to keep his header to be able to proceed the response, so the purpose of my aggregation strategy is to keep the original header.
  I set the .stopOnException() option because I do not want to run step 2 if step 1 is not ok.
  I throw exception with the following way in subroutes :</p>
  
  <pre><code>.choice()
    .when(not(successResponsePredicate))
      .to("log:com.sdmo.Error?level="+LOG_LEVEL)
      .throwException(new Exception("copyItemError"))
    .otherwise()
      .to("mock:CopyItemSuccess")
   .end();
  </code></pre>
  
  <p>Now I want to handle the exception in the aggregation strategy and compute a suitable error message to my web-service response.</p>
  
  <p>If I define an exception behavior with the onException the exchange does not return to the aggregation strategy, I think I had to remove the stopOnException option, but I don't know how configure my aggregation strategy to skip the following multicast step</p>