title: Enforce AllowedPattern for parameter of type CommaDelimitedList in Cloudformation script
body: <p>I'm trying to enforce an allowed pattern with regex on my parameter, but when I try to build my stack, I get the following error message:</p>
  
  <blockquote>
    <p>Template validation error: Template error: Parameter 'myParam' AllowedPattern must be on a parameter of type String</p>
  </blockquote>
  
  <p>This is my Parameter definition:</p>
  
  <pre><code>"myParam": {
     "Description": "this is my param",
     "Type": "CommaDelimitedList",
     "AllowedPattern": "\\+[0-9\\-\\ ]+",
     "MinLength": "1"
   }
  </code></pre>