title: Apache Camel - all headers are lost except String during routing to ActiveMQ
body: <p>I am setting a List in exchange object's header with other couple of headers and routing it to <code>ActiveMQ</code>. </p>
  
  <pre class="lang-java prettyprint-override"><code>exchange.getOut().setHeader("testList", testList);
  exchange.getOut().setHeader("testObject", testObject); 
  exchange.getOut().setHeader("header1", "value1");  
  exchange.getOut().setHeader("header2", "value2");
  </code></pre>
  
  <p>In the next route when I access the exchange object's header, <code>"testList"</code> and <code>testObject</code> are not present ! But remaining headers are present (<code>exchange.getIn().getHeader</code>).</p>
  
  <p>Can't we send any header ( list or any other object) except String ?</p>