java - Best way to hack the return type on an implemented method? -

i'm implementing service through maven dependency takes data , spits out @ virtual location, provided conforms strict type requirements. however, i've swapped out 1 of fields (let's call field buzz , implementation of buzzer) , wondering if can make work rest of service.

the service call factory requires type buzz , diff between buzz , buzzer few added member fields. there hack can make factory accept buzzer? looking through code, service not seem dependent on hashcode of buzz being correct.

edit: examples

class buzz {     public string id    public string name    public string title    public iterable<profile> profiles      public myconstructor(string id, string name, string title, iterable profile)    {    this.var = var;    } } 

and

class buzzer {    public string id    public string name    public string title    public profile profiles     public myconstructor(string id, string name, string title, profile profiles)    {    this.var = var;    } } 

where profile defined object

if can have buzzer extend buzz, ideal.

if can't (for example if 3rd party library , declared final class), hack solution "acquire" buzz instance (that depend on specific scenareo.. need more info more specific). , modify buzz property through reflection.

something this:

string buzz = null;  // assuming buzz field string in example field fbuzz = null; try {     class<?> cbuzz = thebuzzinstance.getclass();     fbuzz = cbuzz.getdeclaredfield( "buzz" );     fbuzz.setaccessible( true );     buzz = ( string ) fbuzz.get( thebuzzinstance );      string newbuzz = "hacked!";     fbuzz.set( thebuzzinstance, newbuzz ); } catch( exception e ) {     // todo: error handling }