How to teach Java Concurrency Java Junior Spring Developer?

Question

Java

Hello. The question is this. How deep do you need to study Concurrency if you are applying for a Java Junior position on the Spring stack? It's just that they will most likely ask about IO and about Collections and about Concurrency at the social security. And if in the case of the first two topics, nothing particularly causes difficulties, then on the last topic there are just tons of information everywhere and everyone.
And here it is clear that you need to know what the Thread class is, the Runnable interface, how to start a thread, about the concept of a monitor - synchronized, wait, notify (all). Everything is very clear here. But how to learn completely, or at least most of the chips from the java.util.Concurrent package, I can’t imagine something yet.
On YouTube there is a Golovach course on this topic. So there are 16 lessons of 2-3 hours each. I can try to cram all this into my head, but is it necessary in this case? It's just that in parallel you need to strengthen yourself on issues in Spring, Hibernate, SQL ... , and then this ton of information falls on your head.