vtkvmtkCenterlineBranchExtractorfunction bug

hi, i use vtkvmtkCenterlineBranchExtractor to calculate branch centerline,but i find there have bug that is the number of points is different the last offset value
有中心线分支提取
and i don’t use the function i can get the same number.
没有中心线分支提取
can anyone tell me why that happens?
thank you