JPA beyond copy paste by Jakub Kubrynski https://youtu.be/EZwpOLCfuq4 - this is video might be a little bit outdated but still contains a lot of useful tips, the content of this video is described here:
Vlad Mihalcea is Java Champion and author of probably the best book about Hibernate. His blog and tutorials are great.
List vs Bag vs Set
equals & hashcode and UUID usage
JPA 2.2 Streaming (fancy stuff)