it's not a big issue- you could convert algorithmic (non framework-based) code really easily, the syntax is very similar, the objects are very similar and in many places near-identical.

someString.equals(someOtherString)... is the biggest wtf you're going to run into, or possibly Integer.x vs 3.ToString(), for example.

Eclipse is a stinker. But it's not unsurmountable.

The bigger issue, for me, was Maven (or gradle), and the OMGWTF, I just want a build! I cannot guarantee I can take any random project that's functioning on your system and get it going on my systems within a day. Sometimes it's been days of headscratching and trying various things but it could be our harshly locked-down environment.

The biggest issue, overall, is the frameworks- we're using SpringBoot, which is generally fine, but it's massive and filled with AOP magic. God help you if you get little thing wrong- which you will because you don't know it...