title: Require array to contain at least one element in Swagger Schema Object definition
body: <p>I'm having a Schema Object definition like this in my <code>swagger.yaml</code>:</p>
  
  <pre><code>User:
    type: object
    properties:
      username:
        type: string
        description: the user name
      colors:
        type: array
        items: {
          type: string,
          enum: [ "red", "blue", "green" ]
        }
        description: user must have one or more colors associated
    required:
      - username
      - colors
  </code></pre>
  
  <p>However, the generated server still happily accepts POST requests using this schema object as required body parameter that do not contain any <code>colors</code> field.</p>
  
  <p>Can I configure Swagger in a way that the <code>color</code> field is always required in a <code>User</code> schema object and ideally also must contain at least one or more items from the enum?</p>