Program: 39895
Project: 39895
Buggy source:
@Override public void authorize(CompletionHandler<String> handler){
  checkNotNull(handler,"String_Node_Str");
  if (mJwtAuthCode == null || mJwtAuthCode.isEmpty()) {
    handler.onError(new SparkError(UNEXPECTED_ERROR,"String_Node_Str"));
    return;
  }
  mAuthService.getToken(mJwtAuthCode).enqueue(new ErrorHandlingCallback<JwtToken>(){
    @Override public void success(    Response<JwtToken> response){
      mToken=response.body();
      if (mToken == null)       handler.onError(new SparkError(CLIENT_ERROR,response.errorBody().toString()));
 else {
        if (mToken.getAccessToken() != null && !mToken.getAccessToken().isEmpty()) {
          handler.onComplete(mToken.getAccessToken());
        }
 else {
          handler.onError(new SparkError(UNEXPECTED_ERROR,"String_Node_Str"));
        }
      }
    }
    @Override public void unauthenticated(    Response<?> response){
      handler.onError(new SparkError(UNAUTHENTICATED,Integer.toString(response.code())));
    }
    @Override public void clientError(    Response<?> response){
      handler.onError(new SparkError(CLIENT_ERROR,Integer.toString(response.code())));
    }
    @Override public void serverError(    Response<?> response){
      handler.onError(new SparkError(SERVER_ERROR,Integer.toString(response.code())));
    }
    @Override public void networkError(    IOException e){
      handler.onError(new SparkError(NETWORK_ERROR,"String_Node_Str"));
    }
    @Override public void unexpectedError(    Throwable t){
      handler.onError(new SparkError(UNEXPECTED_ERROR,"String_Node_Str"));
    }
  }
);
}

Fixed version (ground truth):
@Override public void authorize(CompletionHandler<String> handler){
  checkNotNull(handler,"String_Node_Str");
  if (mJwtAuthCode == null || mJwtAuthCode.isEmpty()) {
    handler.onError(new SparkError(UNEXPECTED_ERROR,"String_Node_Str"));
    return;
  }
  mAuthService.getToken(mJwtAuthCode).enqueue(new ErrorHandlingCallback<JwtToken>(){
    @Override public void success(    Response<JwtToken> response){
      mToken=response.body();
      if (mToken == null)       handler.onError(new SparkError(CLIENT_ERROR,response.errorBody().toString()));
 else {
        if (mToken.getAccessToken() != null && !mToken.getAccessToken().isEmpty()) {
          mToken.shoudlRefetchTokenNow();
          handler.onComplete(mToken.getAccessToken());
        }
 else {
          handler.onError(new SparkError(UNEXPECTED_ERROR,"String_Node_Str"));
        }
      }
    }
    @Override public void unauthenticated(    Response<?> response){
      handler.onError(new SparkError(UNAUTHENTICATED,Integer.toString(response.code())));
    }
    @Override public void clientError(    Response<?> response){
      handler.onError(new SparkError(CLIENT_ERROR,Integer.toString(response.code())));
    }
    @Override public void serverError(    Response<?> response){
      handler.onError(new SparkError(SERVER_ERROR,Integer.toString(response.code())));
    }
    @Override public void networkError(    IOException e){
      handler.onError(new SparkError(NETWORK_ERROR,"String_Node_Str"));
    }
    @Override public void unexpectedError(    Throwable t){
      handler.onError(new SparkError(UNEXPECTED_ERROR,"String_Node_Str"));
    }
  }
);
}