Whole architecture of Fleet is distributed, so we need a small binary without dependencies that could be uploaded to the dev container. All the access goes through that binary (even in local case)
It's interesting and says something about the state of tooling that, in response to those requirements, it was easier to switch to an entirely different language and ecosystem than it was to build off the existing work and convince the toolchain you were using to produce output with those properties.
Is it / does it? I thought the JRE as a deploy-time dependency was the very first conscious tradeoff one makes with Java, and always has been.
JDK is modular now and ecosystem is moving towards jlinked application. So no need for jdk on the target machine.
Well, you can make standalone binaries with both Kotlin and Java these days, so this may be related to when Fleet was started rather than how you'd do it in 2021.