How to define a loop operation in a camel route by YAML XML

Issue

This is a XML DSL. How to write a code by YAML DSL.

<?xml version="1.0" encoding="UTF-8"?>
<!-- camel-k: language=xml -->

<route>
  <from uri="direct:start"/>
  <loop doWhile="true">
    <simple>${body.length} &lt;= 5</simple>
    <to uri="mock:loop"/>
    <transform>
      <simple>A${body}</simple>
    </transform>
  </loop>
  <to uri="mock:result"/>
</route>

How to define a loop operation in a camel route by YAML XML?