title: Query parameter with comma-separated strings in Swagger returns structural error
body: <p>I am trying to define a query parameter in Swagger with comma-separated strings from a predefined set of items like <code>?fruits=Apples,Oranges,Bananas</code> but I get the following error from the swagger editor </p>
  
  <blockquote>
    <p>should NOT have additional properties   additionalProperty: style,
    explode</p>
  </blockquote>
  
  <p>What I am trying in the Swagger Editor is:</p>
  
  <pre><code>    - in: query
        name: fruits
        style: form
        explode: true
        required: false
        description: Filter by fruits
        type: array
        items:
          type: string
          enum:
            - Apples
            - Oranges
            - Bananas
  </code></pre>