title: Merge multiple string json into one java
body: <p>I have multiple json strings like:</p>
  
  <p>JSON 1: </p>
  
  <pre><code>{
  "a":"test1",
  
  "b":"test2"
  }
  </code></pre>
  
  <p>JSON 2: </p>
  
  <pre><code>{
  "b":"test3",
  
  "c":"test4"
  }
  </code></pre>
  
  <p>I want final json as:</p>
  
  <pre><code>{
  "a":"test1",
  
  "b":["test2","test3"],
  "c":"test4"
  }
  </code></pre>
  
  <p>How can I do this in java?</p>