Returns the result of applying this SuccessContinuation to Task.

The SuccessContinuation only happens then the Task is successful. If the previous Task fails, the onSuccessTask continuation will be skipped and failure listeners will be invoked.

   private Task<String> doSomething(String string) {
     // do something
   }
   task.onSuccessTask(new SuccessContinuation<String, String>() {
     @NonNull
     @Override
     public Task<String> then(String string) {
       return doSomething(string);
     }
   });