That's a feature that will avoid mixing various Kotlin versions 😉 It will be properly documented.

currently it does the opposite, until I noticed it I had both 1.1.51 and 1.1.61 in my project 😕

stdlib-jre8

(which I declared) was 1.1.61 and transitive

stdlib

and

stdlib-jre7

where 1.1.51 (due to spring)