27.7.3. Java
No OpenJDK package as of 2018.08: https://stackoverflow.com/questions/28874150/buildroot-with-jamvm-2-0-for-java-8/59290927#59290927 partly because their build system is shit like the rest of the project’s setup.
Unmerged patch at: http://lists.busybox.net/pipermail/buildroot/2018-February/213282.html
There is a JamVM package though https://en.wikipedia.org/wiki/JamVM which is something Android started before moving to Dalvik,
Maybe some day other Android Java runtimes will also become compilable. Maybe, since Android is also shit.