Here’s the link to my code (sorry I can’t post a real link, please copy-n-paste it):
https://github.com/inc-lc/ilc-scala/blob/9a158ae7757eab62b91ef2fd2196adda810f6ad5/src/main/scala/ilc/feature/bags/Library.scala#L11-L37
And here’s the link to docs: HashMap.merged docs