## What happened
Initializing the Harness Java SDK CfClient in a Spring Boot project throws java.lang.NoSuchMethodError: kotlin.collections.ArraysKt.copyInto from okio. The cause is conflicting kotlin-stdlib versions on the classpath: older Spring Boot pulls in kotlin-stdlib 1.2.x, which clashes with what okhttp 4.9.x needs.
## The fix that worked
Upgrade Spring Boot to 2.7.x if you can, which brings a compatible kotlin-stdlib. If not, force a newer kotlin-stdlib by adding it directly to your dependencies. This is a classpath conflict, not a bug in the SDK.