Henryk, Sorry for the confusion - my error handler is written in Groovy, and the definition of the exception handler is as follows:
// N.B. This method implicitly returns null def exception(Exchange exchange) { System.out.println("Exception: " + exchange.getIn()); } In Java this is effectively: Object exception(Exchange exchange) { System.out.println("Exception: " + exchange.getIn()); return null; } So I guess that explains that! Thanks again for your help, Alex