As a data point, I started actual-programming in Perl 15 years ago, started on Rails about 10 years ago, and am now taking Java classes to get some interview-question fundamentals under my belt, since Rails is historically a recovery path for Java programmers. I don't know how it works the other way around, but for me Java has been pretty easy after writing Ruby for some years.
And you're coming into java at a better time - lambdas and inferred generic types for contractor calls reduce the boiler plate a little.
I work on a big java project - I'd love to write new stuff in kotlin though.
It's really interesting to be going in the other direction. People learn Java/C++ in university, then get jobs writing PHP or whatever. I can't imagine how cynical that would make a person, at the very least against their student loans! Not to language-war, natch. But going "in reverse" really feels like an excavation. "Interesting, this is what they had (have, like in your case) to do before langs/frameworks evolved!"
