Level-0 sorting for KllItemsSketch<T> is not based on Comparator<T>

[fanyang01]

datasketches-java/src/main/java/org/apache/datasketches/kll/KllItemsHelper.java

Lines 436 to 438 in 8ae234b

	if ((curLevel == 0) && !isLevelZeroSorted) {
	Arrays.sort(inBuf, adjBeg, adjBeg + adjPop);
	}

The Arrays.sort API in the above code

sorts the specified range of the specified array of objects into ascending order, according to the natural ordering of its elements. ... All elements in this range must implement the Comparable interface`.

It appears that Arrays.sort(inBuf, adjBeg, adjBeg + adjPop, comp) should be called instead.

[leerho]

Thank you!
This was a bit subtle. It only occurs during merge, when a compaction is required, and when the object T cannot be naturally ordered.
Will fix this and add a test for it.

[jmalkin]

This has been merged into the main branch (next release with this still TBD). It was also back-ported into the 5.0.X branch, and I'm working on starting a release vote for a v5.0.2 right now, which will include this fix.

[fanyang01]

Thank you very much! I have checked the related changes and the test case looks great. I will wait for the next release.