Great repository! What should I change to support zero-length intervals and return adjacent interval too?

[ndvbd]

I modified the overlaps function to be able to return intervals that touch an interval on one side:

default boolean overlaps(Interval o) {
        return end() >= o.start() && o.end() >= start();
    }

However it doesn't work when a 0 length interval touches a query interval on one side. What did I miss?