https://docs.gradle.org/current/userguide/organizing_gradle_projects.html#sec:build_sources
" The directory buildSrc is treated as an included build. Upon discovery of the directory, Gradle automatically compiles and tests this code and puts it in the classpath of your build script. For multi-project builds there can be only one buildSrc directory, which has to sit in the root project directory. buildSrc should be preferred over script plugins as it is easier to maintain, refactor and test the code."
…and…
https://docs.gradle.org/current/userguide/composite_builds.html#composite_build_intro
“A build that is included in a composite build is referred to, naturally enough, as an “included build”. Included builds do not share any configuration with the composite build, or the other included builds. Each included build is configured and executed in isolation.”
That being said I have noticed that sometimes my IDE does not recognize changes in buildSrc/build.gradle.kts
I suspect this is due to an oversight by the Intellij people.