This looks interesting, I worked with Java some time ago, but haven't touched it for some time. I guess since the graph is really not that intuitive this really describes how complicated can be learning Java!
To name 2:
https://devdocs.io/openjdk~21/java.base/java/util/gregorianc...
https://devdocs.io/openjdk~21/java.base/java/net/url#equals(...