jackson-module-kotlin memory issue

This repository shows a potential memory issue with jackson-module-kotlin, or more specifically the KotlinModule.

When running Main.kt, I get output similar to:

Using kotlinObjectMapper
    Reading KRepository
      -> Before: 2.97MiB; After: 400.03MiB; Allocated: 397.06MiB
    Reading JRepository
      -> Before: 5.31MiB; After: 206.31MiB; Allocated: 201.0MiB
Using plainObjectMapper
    Reading KRepository
      -> Before: 5.49MiB; After: 206.49MiB; Allocated: 201.0MiB
    Reading JRepository
      -> Before: 5.56MiB; After: 206.56MiB; Allocated: 201.0MiB

This shows me that using the KotlinModule with a Kotlin data class causes approximately twice the memory overhead than when using a Java record or when not using the KotlinModule at all.

Running

With JDK17 or higher and Maven:

MAVEN_OPTS="-Xms2G -Xmx2G" mvn clean verify exec:java

The -Xms and -Xmx are useful to try and avoid garbage collections while the test loop is running.