title: What is the convention in JSON for empty vs. null?
body: <p>I know that in most programming scenarios, the preference is for empty collections to null collections when there are 0 elements.  However, most languages that consume JSON (like JavaScript) will treat empty lists/objects as true and null ones as false.  For example this would be both true and an object in JavaScript:</p>
  
  <pre><code>{
      "items_in_stock": {"widgets":10, "gadgets": 5}
  }
  </code></pre>
  
  <p>But this is also true:</p>
  
  <pre><code>{
      "items_in_stock": {}
  }
  </code></pre>
  
  <p>And this is false:</p>
  
  <pre><code>{
      "items_in_stock": null
  }
  </code></pre>
  
  <p>Is there a convention on empty objects/lists for JSON? And what about for numbers, booleans, and strings?</p>