Go with your developers. Looks like your team has already decided to go with Python as a scripting language. Follow the below activities to get hands-on with Java for automation scripting.
-Answer Java related automation testing questions.
-Prepare Python and Java Selenium Cheat sheets.
-Publish automation testing blog posts using Java and Python scripting languages.
-Explore Page Object Libraries.
-Publish an automation testing utility which is useful for automation testing community in Maven central repository.
Test Automation Architect at Codoid.