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But to the OP's question, many, if not the majority, of those technologies are written in Java. Definitely the majority are on the JVM, since a few of the non-Java ones are Scala and Clojure.

I think the simple answer is that while lots of people do not love programming in Java, it can be attractive for projects that want relatively good performance without trying to implement a system in C++. There are also a lot of tools and companies that have investments in deploying JVM applications.