here is one: https://github.com/questdb/questdb. Disclaimer, I work on this project. Main reason we use Java is speed of development (which increased with amount of base libraries written) and ease of testing.
Would you do it again? Coming from C/C++ first, Java then and coming to C# it just feels so much more pragmatic with f.ex. struct(s), slices and stackalloc (and unsafe blocks with pointers in a pinch) allowing for GC less programming w/o resorting to turning pointers to integers and using function calls for memory access all around. (Noticed that you do i guess query compilation via the ASM toolkit?)
It is a good question. I feel there is a happy medium where boilerplate is in Java and more intricate data processing routines are in C++. Makes both worlds simpler. I like C++ better. Those things you mentioned - Java truly sucks at indeed, but you don't always need them. When it comes to IDE, testing, compilation speed, cross platform code and finding talent - Java is way easier than C++.
Yeah i see that outlook, my comment was actually mostly about C# (been using it for the past year and these things above are in it as well as all the base being Java-ish)