title: Camel rest route not returning status code on exception
body: <p>I have created a camel route with the following exception handling:</p>
  
  <pre><code>onException(BadRequestException.class)
      .handled(true)
      .process(exchange -&gt; {
          System.out.println("Reached processor");
          System.out.println(exchange.getIn().getBody(String.class));
      })
      .setHeader(Exchange.HTTP_RESPONSE_CODE, constant(HttpStatus.BAD_REQUEST));
  </code></pre>
  
  <p>I make a request to <code>http://localhost:8080/services/rest/endpoint?key=value</code></p>
  
  <p>In a bean, I have some validation that says that two query parameters are required, <code>key</code> and <code>keyTwo</code>. <code>keyTwo</code> isn't present, so I throw a <code>BadRequestException</code>:</p>
  
  <pre><code>public void assertRequiredParametersPresentOnExchange() throws BadRequestException {
      try {
          requiredParameters.stream()
              .forEach(p -&gt; assertNotNull(p));
      } catch (IllegalArgumentException e) {
          throw new BadRequestException(e.getMessage());
      }
  }
  </code></pre>
  
  <p>When I execute the URL, I can see <code>Reached processor</code> output from the exception handler above, but then nothing happens. Postman waits for a reply for ~60 seconds and then gives me status code 23.</p>
  
  <p>What am I missing here? MEP? Setting some property on the exchange?</p>