Mappie can generate reports containing Kotlin-like representations of the generated mappers. This must be enabled explicitly, see Gradle Configuration or Maven Configuration for more details.
The mappers are generated in the back-end of the compiler, from the so-called Intermediate Representation (IR). These reports are pretty-printed from the IR, and thus cannot be used as actual Kotlin code.
When Mappie's pretty-printing fails, the Kotlin compiler's pretty-printer will be used instead. However, this produces an abstract representation. Note that this should never happen and should always be considered a bug in Mappie.