title: Skip level when parse with Gson
body: <p>I have some json format look like:</p>
  
  <pre><code>{
  "root": {
      "user": {
          "name":"Name",
          "age":99,
          "another_obj": {
              "f1":"abc",
              "f2":1
          }
      }
  },
  "result_code": 0
  }
  </code></pre>
  
  <p>I create some model look like:</p>
  
  <pre><code>class User {
  private String name;
  private int age;
  @SerializedName("detail")
  private Detail
  }
  
  class Detail{
     // Define something.
  }
  </code></pre>
  
  <p>finally I create class name UserWapper.</p>
  
  <pre><code>class UserWapper {
  @SerializedName("root")
  private User user;  
  }
  </code></pre>
  
  <p>To parse json:</p>
  
  <pre><code>String json = "STRING_JSON_ABOVE";
  Gson gson = new Gson();
  UserWrapper uw = gson.fromJson(json, UserWrapper.class);
  </code></pre>
  
  <p>But current I don't want create class Wrapper. Because I have many many class. If create WrapperClass -> :|</p>
  
  <p>I want to do something like:</p>
  
  <pre><code>User u = gson.fromJson(json, User.class).
  </code></pre>
  
  <p>(Note: I can't change format data json from server. I also gg search something custom gson adapter but I don't find a way for skip "level" another field).</p>