title: JSON duplicate key, validate using java(spring)
body: <pre><code>[
      {
      "id" : "Unique_Id25",
      "firstName" : "Test Name",
      "firstName" : "Test Name 2",
      }
  ]
  </code></pre>
  
  <p>Above I have an example of a duplicate key, <code>firstName</code>. I use Postman and it warns that a duplicate key exists, but the POST request passes as I don't currently validate for it.</p>
  
  <p>So I'm asking if there's a cool java/spring way of checking for this duplicate and throwing an exception. </p>
  
  <p>Otherwise I'll try to build these JSON keys into an array and looping through.</p>