[kev009]

The things you identified you will need to know and would be proficient knowing them. JDBC not so much but depending on the libs you use, you could be using it indirectly. Same story with maven, knowing how to look up stuff on mavencentral will help but beyond that you don't need to care.

Knowing a little Java would help when calling into Java libs but an IDE like IntelliJ that can help you understand conversions would do well too.

A lot of people convert from languages like Perl and Ruby without tremendous difficulty. I can only recommend diving in to make a real assessment, prejudices and phobias will otherwise prevent understanding.