Canucks' 2007 first-rounder, Patrick White, was the exact same situation as Jankowski: Traded to San Jose, who chose not to sign him after 4 years of college. San Jose received the 25th pick in the second round of the 2012 draft in compensation and picked Chris Tierney.
Conner Bleackley is another a recent example. Drafted by Colorado in 2014. In 2016, he was traded to Arizona specifically so they could get the compensatory pick:
https://www.thescore.com/nhl/news/1036744 The Coyotes had no intention of offering him a contract.
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Looking at what the Flames would have received in compensation had they chosen not to sign Jankowski (21st pick in round 2 of the 2017 draft), no one picked anywhere near that spot has done much of anything in the NHL yet. That was 4 years ago, so Treliving probably made the right choice since Jankowski played over 200 games here.