title: Setting an Attribute as a "string" or null in JSON Schema with a maxLength
body: <p>I'm trying to create a JSON schema that allows for a nullable attribute. For example, I want the following JSON to be valid:</p>
  
  <pre><code>{
   "some_name" : null
  }
  </code></pre>
  
  <p>with the following schema:</p>
  
  <pre><code>{
    "type": "object",
    "properties": {
      "some_name": {
        "type": [
          "string",
          null
        ],
        "maxLength": 100
      }
    }
  }
  </code></pre>
  
  <p>However, it's invalid as it thinks that "null" can't have a maxLength. Is there a good way to do this? I wish there was a "nullable" attribute, or something of the sort!</p>