title: How to create a configuration with bot array and scalar prototypes
body: <p>I have the following configuration:</p>
  
  <pre><code>my_project:
      options:
          key1: value1
          key2: value2
          key3: value3
          key4: [sub1, sub2, sub3, sub4]
  </code></pre>
  
  <p>These options are not known by my extension, I would like to get an associative array:</p>
  
  <pre><code>array(
      "key1"=&gt;"value1",
      "key"=&gt;"value2",
      "key3"=&gt;"value3",
      "key4"=&gt;array("sub1","sub2","sub3","sub4") 
  );
  </code></pre>
  
  <p>My tree looks like:</p>
  
  <pre><code>$rootNode
      -&gt;addDefaultsIfNotSet()
      -&gt;children()
          -&gt;arrayNode('options')
              -&gt;useAttributeAsKey('key')
              -&gt;treatNullLike(array())
              -&gt;prototype('scalar')-&gt;end()
          -&gt;end()
      -&gt;end();
  </code></pre>
  
  <p>The problem is that with the key/value "key4" I have an exception (this is normal as the prototype is 'array').</p>
  
  <p>So my question is : How can I mix both scalar and array options?</p>