How to custom @FeignClient Expander to convert param？
<p>Feign default expander to convert param：</p>

<pre><code>final class ToStringExpander implements Expander {

    @Override
    public String expand(Object value) {
      return value.toString();
    }
  }
</code></pre>

<p>I want custom it to convert user to support <code>GET</code> param, like this</p>

<pre><code>@FeignClient("xx")
interface UserService{

   @RequestMapping(value="/users",method=GET)
   public List&lt;User&gt; findBy(@ModelAttribute User user);
}

userService.findBy(user);
</code></pre>

<p>What can i do?</p>