copy() in abstractOptionHandler clashes with copy() in OptionsHandler

In org.apache.samoa.streams package, I tried to add a new TwitterStream source so I coded a new class:

public class TwitterStreamInstance extends AbstractOptionHandler implements
InstanceStream {
}

Problem is that the copy object which in this case should be overriden becomes a bottleneck:

@Override
public MOAObject copy()

{ return null; }

This very same issue happens when I opened FileStream.java in the same package.