There is a corner case where if the connector is just started and the first mining query returns no results, the buffer is empty and the end scn will transition to the start scn. If the end scn is close to the current scn and there is asynchronous flushes, there may be the possibility that events near or at the end scn could be omitted from the stream.

While we may want to consider allowing the mining window to grow, we probably should see whether we can determine a safe SCN to advance to to avoid an ever growing window in the case of SCN gaps.