title: What is the correct way to declare a date in an OpenAPI / Swagger-file?
body: <p>What is the correct way to declare a date in a swagger-file object? I would think it is:</p>
  
  <pre><code>  startDate:
      type: string
      description: Start date
      example: "2017-01-01"
      format: date
  </code></pre>
  
  <p>But I see a lot of declarations like these:</p>
  
  <pre><code>  startDate:
      type: string
      description: Start date
      example: "2017-01-01"
      format: date
      pattern: "YYYY-MM-DD"
      minLength: 0
      maxLength: 10
  </code></pre>
  
  <p>Thanks.</p>