title: Java merge Objects (Json, ObjectMapper)
body: <p>I wonna merge two POJO objects:</p>
  
  <pre><code>MyBean old = new MyBean();
  MyBean diff = new MyBean();
  </code></pre>
  
  <p>In Json they look this: </p>
  
  <pre><code>diff: {"nat_udp_update_time":333}
  old: {"nat_udp_update_time":15,"static_sip_local_port":1111}
  </code></pre>
  
  <p>result needed:</p>
  
  <pre><code>old: {"nat_udp_update_time":333,"static_sip_local_port":1111}
  </code></pre>
  
  <p>How i make this with use ObjectMapper or another lib? </p>