title: How to set path variables in camel-http4
body: <p>I have a camel-spring-boot project where I load the destination url from a yml file with Spring's @ConfigurationProperties. As my destination is a HTTP url I am using camel-http4 component.</p>
  
  <p>Now my URL is <a href="https://example.com/students/" rel="nofollow noreferrer">https://example.com/students/</a>{id}/subject/{name}, which means I have to pass id and name parameter as path variables (not query parameter). My question is how can I pass these parameters? [Note: I can not put the URL in DSL or XML, it must be there in application.yml]</p>
  
  <p>However, as a solution </p>
  
  <pre><code>//in some processor before toD()
  headers.put("id", id);
  headers.put("name", name);
  
  //in yml
  destination: https4://example.com/students/${header.id}/subject/${header.name}
  </code></pre>
  
  <p>But while loading this property from yml, Spring tries to evaluate ${header.id} as Spel expression (and throwing error that it could not find it) where as I mentioned it as Camel's simple expression. This same expression works with toD() if I use DSL, but not from yml.</p>
  
  <p>Please let me know, if my approach is proper or not? If it is the way, then how can I get rid of this problem. Thanks in advance.</p>