Reaching Spring & Hibernate potential

Disclaimer: Excuse me in advance if this question should be posted elsewhere in stackexchange

I was a decent J2SE developer during University. From then i switched over to Python/Matlab due to my focus on Machine Learning. In my current job i work as a technology consultant and want to get involved in software development project we undertake. My company relies almost exclusively in the Spring/Hibernate/JSP trio.

What is the "shortest" way in terms of concepts and reading is should make from J2SE and POJOs to Spring/Hibernate ?

I want to avoid any JEE unnecessary burden but unsure of "what" exactly i should avoid and what is more or less required from JEE before focusing on Spring.