title: JSONSerializer.toJSON the result is empty
body: <p>I am trying to serialize a Java Object to a string, in JSON format. I thought that the JSONSerializer was the right answer, but when I call it, the result has a size equal to 0.
  For the moment my object to parse is really basic:</p>
  
  <pre><code>public class Location {
      public double _latitude;
      public double _longitude;
  
      public void setLatitude(double latitude){
          this._latitude = latitude;
      }
      public void setLongitude(double longitude){
          this._longitude=longitude;
      }
   }
  </code></pre>
  
  <p>And my call is pretty simplistic too:</p>
  
  <pre><code>JSONObject jsonResponseObject = (JSONObject) JSONSerializer.toJSON(location)
  </code></pre>
  
  <p>Reading the <a href="http://json-lib.sourceforge.net/apidocs/net/sf/json/JSONSerializer.html#toJSON%28java.lang.Object%29" rel="nofollow">documentation</a>, I thought that it would just magically work with any object... </p>
  
  <p>Any help will be appreciated</p>