title: List as map value in grails
body: <p>I need to populate a Map so that:</p>
  
  <ul>
  <li>The Key is a String</li>
  <li>The Value is a List of Strings</li>
  </ul>
  
  <p>The process is to go through all the records in a table that has two text fields : "parameter" and "value". "Parameter" is not unique an has many duplicates. So what I intent to do is:</p>
  
  <pre><code>def all = MyTable.findAll()
  def mymap = [:]
  
  all.each {
    // add to mymap the element "it.value" to the list that has "it.parameter" as key 
  }
  </code></pre>
  
  <p>Any clues ?</p>
  
  <p>Thanks</p>