aeron-archive/src/main/java/io/aeron/archive/client/ReplayMerge.java
public int poll(final FragmentHandler fragmentHandler, final int fragmentLimit)
    {
        doWork();
        return null == image ? 0 : image.poll(fragmentHandler, fragmentLimit);
    }
public int poll(final FragmentHandler fragmentHandler, final int fragmentLimit)
    {
        doWork();
        return null == image ? 0 : image.poll(fragmentHandler, fragmentLimit);
    }
Poll the {@link Image} used for the merging replay and live stream. The {@link ReplayMerge#doWork()} method
will be called before the poll so that processing of the merge can be done.

@param fragmentHandler to call for fragments
@param fragmentLimit for poll call
@return number of fragments processed.