title: Why would a map helper extending hashmap be useful? Why not just use hashmap?
body: <p>In a large java code base in my recent job, I see the below code:</p>
  
  <pre><code>public class MapHelper extends HashMap&lt;String, Object&gt;{
  
      private static final long serialVersionUID = 1L;
  
      public MapHelper() {
          super();
      }
  
      public MapHelper(MapHelper mh) {
          super(mh);
      }
  
      public MapHelper as_dict(String key) {
          return (MapHelper)this.get(key);
      }
  }
  </code></pre>
  
  <p>I'm not sure how this would be useful. Are there examples you have that could shed light on the above MapHelper's usefulness? </p>