title: How copy selected property (not all) from camel to activiti
body: <p>Camel scenario:</p>
  
  <ul>
  <li>read file</li>
  <li>do something e.g store content in database</li>
  <li>run activiti process and pass variable from previous step</li>
  </ul>
  
  <p>RouteBuilder:</p>
  
  <pre><code>from("file:/home/work/Inbox")
  .to("bean:sourceFileService?method=storeFile")
  .to("activiti:Receive?copyVariablesFromProperties=true")
  </code></pre>
  
  <p>During call bean sourceFileService property 'sourceFileId' is set.
  This variable should be transferred to the process Receive as variable.</p>
  
  <p>If I don't use copyVariablesFromProperties any variable is not set in process.
  One the other side when copyVariablesFromProperties=true then camel try pass all properties and exception occurs:</p>
  
  <p>ActivitiException: couldn't find a variable type that is able to serialize GenericFile</p>
  
  <p>(because one of property is object represents read file, there are 7 other unwanted property )</p>
  
  <p>How pass only selected property to activiti endpoint or in camel any next 'to' ?</p>