They use Java - a language I literally haven’t used since maybe a year after it was introduced.
I used ChatGPT to create the source code for the sample based on my specifications including Junit tests, the build with Maven, the Dockerfile - everything.
Of course it got a few things wrong and missed steps and I had to keep pasting in error messages until it got it right. But it was still faster than trolling the internet.
Of course I was very up front with the client that the Java pieces were all generated by ChatGPT.