Not to mention their UX is horrendous. You never hear people wanting to copy their UX. With the size of their company they should be able to produce better.
Jenkins comes to mind, Jira of course, and just about any other Java project's website still looks like it is from the 90s.
Also, all the big internet companies use Java, basically. You're using Google, Amazon, Twitter, Netflix, etc. products and you're using Java. Do you also hate those? :)
Furthermore, Java is mostly server side at this point so I'm not sure your UI complaint is really valid...