calcite-core 1.28.0 now depends on kotlin-stdlib?

[Zoltan Farkas]

I see that the latest release of calcite-core brings in kotlin-stdlib as a 
dependency.,

    <dependency>
      <groupId>org.jetbrains.kotlin</groupId>
      <artifactId>kotlin-stdlib-jdk8</artifactId>
      <version>1.5.31</version>
    </dependency>

I looked over the release notes, and I cannot find anything that mentions this, 
anyone knows why is this new dependency required?
(up until 1.27.0 kotlin was only a test dependency)

thanks!

—Z