I want to understand one thing at major companies: Why Java?
Is this a company investment thing, they're in bed with IBM?
Is it a mentallity thing?
Is it a compiled language thing?
Is it a security thing?
It's certainly not a speed thing. Every team I have had experience with working with on a Java platform has taken ages to deliver anything. CMSs that I could build rapidly with the likes of PHP/MySQL take months/years to get off the ground. Change is slow.
Believe me, I have zero experience of working with Java, but I need to understand why they do it. Have you experienced rapid development teams using Java?
Very fast.
Unicode strings.
Some measure of type checking (probably appeals more to large, enterprisey projects). This also makes IDE autocomplete easier.
Lots of libraries.
Cross platform.
And yes, a large pool of developers.
Not too many languages can check off all those boxes, making Java a sweet spot for a lot of enterprise development. Probably not a good fit if you just want to throw together a CMS, though.