Some years back, there was a lively interchange between Polish and Ukrainian historians over the massacres that occurred in Volhynia and Galicia in 1943-44.
Yaroslav Hrytsak characterizes it as the Ukrainian Historikerstreit, referring to an important debate among German historians over the place of the Holocaust in German history. He meant that it was a coming to terms with the dark aspects of the past.
One of the things that emerged clearly from this discussion was that UPA and OUN were responsible for the murder of tens of thousands of Poles in western Ukraine. (Another was that, when possible, armed Poles took a ferocious revenge.)