CASSANALYTICS-180: TokenPartitioner fails to detect range gap in reader

[mansikhara]

No description provided.

[jyothsnakonisa]

Looks good! Please add Changes.txt entry for this patch

[jyothsnakonisa]

Suggested change

	coveringRanges.forEach(uncovered::remove);
	uncovered.removeAll(coveringRanges);

You could use removeAll instead of removing each entry in for loop

[yifan-c]

Sorry for the belated review.

First of all, thanks for adding more test cases.

I think the fix can be much smaller than what's here. The actual bug is just that .filter(Range::isEmpty) in validateCompleteRangeCoverage() is a no-op: Guava's TreeRangeSet never materializes empty ranges in asRanges(), so that filter can never keep anything, and the missing-range check silently always passes.

The minimal and correct fix is:

• Drop the .filter(Range::isEmpty) filter
• Change Range.closed(minToken, maxToken) to Range.openClosed(minToken, maxToken), since sub-ranges everywhere else are open-closed and closed would falsely flag minToken as a gap on an otherwise healthy ring

Would you mind trimming the patch down to that?