title: Java - Merge JSON files
body: <p>I am building an updater util that update my application.
  I need to save my configuration files from the previous version.
  Some of the configurations files are JSON files.
  Is there a way to update the JSON files in a way that i'm keeping the old values
  but if there new objects or keys they will be saved also?</p>
  
  <p>For example:
  Version 1 json file:</p>
  
  <pre><code>{
      "name": "demo",
      "description": "Parse some JSON data",
      "location": "New York"
  }
  </code></pre>
  
  <p>Version 2 json file:</p>
  
  <pre><code>{
      "name": "demo",
      "description": "Parse some JSON data",
      "location": "London",
      "day": "Monday"
  }
  </code></pre>
  
  <p>Expected json file after the merge:</p>
  
  <pre><code>{
      "name": "demo",
      "description": "Parse some JSON data",
      "location": "New York",
      "day": "Monday"
  }
  </code></pre>
  
  <p>Is there a way to do so without any external library?</p>