@Override
 public IConversionJobWithTargetUnspecified to(File target, IFileConsumer callback) {
   return conversionJob.to(target, new FailureAwareFileConsumer(callback));
 }
 @Override
 public IConversionJobWithTargetUnspecified to(IInputStreamConsumer callback) {
   return conversionJob.to(new FailureAwareStreamConsumer(callback));
 }