I'm aware of why they selected Java (mindshare) for their development platform, but that doesn't exactly explain why they coded the majority of their framework

I'm aware of why they selected Java (mindshare) for their development platform, but that doesn't exactly explain why they coded the majority of their framework in Java. Had they used C/C++ the interoperability with other languages for UI based applications would have been trivial with the respective API wrappers in place.