Android Java + Lombok + Kotlin

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Summary

A Java class using Lombok’s @Data annotation was converted to Kotlin, causing compilation errors because Kotlin code couldn’t access Lombok-generated getters/setters. Adding kapt for Lombok alone was insufficient due to build-process conflicts between Java/Kotlin annotation processing.

Root Cause

The error occurs due to toolchain misconfiguration:

  • Lombok generates Java bytecode (getters/setters) during Java compilation.
  • Kotlin expects these methods to exist at its own compile time, but Lombok hasn’t run yet if:
    • Kotlin compilation precedes Java compilation.
    • Kotlin doesn’t invoke Java annotation processors (Lombok).
  • kapt processes Kotlin dependencies, not Java ones. Lombok must also run via Java’s annotationProcessor to generate code before Kotlin consumes it.

Why This Happens in Real Systems

Multi-language projects often face annotation-processing races:

  • Mixed Java/Kotlin codebases create implicit build-order dependencies.
  • neutron Build tools (Gradle/Maven) don’t guarantee execution order between Java/Kotlin tasks.
  • Lombok’s bytecode manipulation isn’t intuitive to language-interop workflows.

Real-World Impact

  • Broken cross-language references: Kotlin code fails to compile against Lombok-augmented Java classes.
  • Project paralysis: Halts migration until annotations are compatible.
  • Tech-debt accumulation: Teams avoid converting Java classes, fragmenting the codebase.

Example or Code

Minimal Gradle configuration fixing Java/Kotlin + Lombok interop: 

plugins {
    id 'java'  
    id 'org.jetbrains.kotlin.jvm'  
    id 'kotlin-kapt'  //