title: Map json field from child object
body: <p>Here is the description of issue to convert Json string to json.</p>
  
  <pre><code>Address{
      private long id;
      private String city;
  }
  
  Employee{
      private long id;
      private String name;
      private Address address;
  }
  </code></pre>
  
  <p>Client will send a request with JSON of employee</p>
  
  <pre><code>{"id": 1, "name": "ABC", "address": {"id": 1, "city": "XYZ"}}
  </code></pre>
  
  <p>Now i want to convert the input json into below format where addressId = id field of Address class.</p>
  
  <pre><code>Output{
      private long id;
      private String name;
      private long addressId; 
  }
  </code></pre>
  
  <p>is there any way to achieve this.
  I have tried Jackson and Gson also.</p>