title: validate array json contains several unordered objects using json schema
body: <h2>Problem</h2>
  
  <p>I want to use json schema draft 7 to validate that an array contains several unordered objects. For example, the array should contains student A, B, regardless of their orders. </p>
  
  <pre><code>[{"name": "A"}, {"name": "B"}] //valid
  [{"name": "B"}, {"name": "A"}] //valid
  [{"name": "A"}, {"name": "C"}, {"name": "B"}] //extra students also valid
  [] or [{"name": "A"}] or [{"name": "B"}] //invalid
  </code></pre>
  
  <h2>Current Attempt</h2>
  
  <p>json schema <code>contains</code> keyword doesn't support a list </p>
  
  <p>json schema <code>Tuple validation</code> keyword must be ordered</p>