title: Invisible character in default string value
body: <p>I am serialising a message which contains some invisible characters in a string. It works just fine but I don’t know if it’s possible to have an invisible character in the default value of the string field.</p>
  
  <p>Something like that: </p>
  
  <pre><code>Message test1 {
      optional string testField = 1 [default = "&lt;STX&gt;"];
  }
  </code></pre>
  
  <p>Is there any solution to do this ?</p>