public boolean isDone() {
        return !(hasNext() || progressToken.hasActive());
    }
Check if the iterator is actually done

@see #hasNext()

@return <code>true</code> <em>iff</em> the bucket source is empty and
there are no pending or active buckets in the progress token.
documentapi/src/main/java/com/yahoo/documentapi/VisitorIterator.java