Configuring kapt to process lombok annotations - kotlin

Question

This is a followup for these questions:
Kotlin doesn't see Java Lombok accessors?
Is kapt supported in maven?
It seems that the kapt has evolved since and now it is even supported in Maven. I am trying this (note the Lombok annotation processor in the config):
<plugin>
<groupId>org.jetbrains.kotlin</groupId>
<artifactId>kotlin-maven-plugin</artifactId>
<version>${kotlin.version}</version>
<executions>
<execution>
<id>kapt</id>
<goals>
<goal>kapt</goal>
</goals>
<configuration>
<sourceDirs>
<sourceDir>${project.basedir}/src/main/java</sourceDir>
<sourceDir>${project.basedir}/src/main/kotlin</sourceDir>
</sourceDirs>
<annotationProcessors>
<annotationProcessor>lombok.core.AnnotationProcessor</annotationProcessor>
</annotationProcessors>
</configuration>
</execution>
...
</plugin>
But it still seems to have no effect and the Lombok #Getter is still ignored as described in the related issues.
Is there anything that can be done?

Answer 1

So, if you wish to use Lombok annotations on Kotlin classes, this should work:
<execution>
<id>kapt</id>
<goals>
<goal>kapt</goal>
</goals>
<configuration>
<sourceDirs>
<sourceDir>src/main/kotlin</sourceDir>
<sourceDir>src/main/java</sourceDir>
</sourceDirs>
<annotationProcessors>
<annotationProcessor>lombok.launch.AnnotationProcessorHider$AnnotationProcessor</annotationProcessor>
</annotationProcessors>
<annotationProcessorPaths>
<annotationProcessorPath>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>${lombok.version}</version>
</annotationProcessorPath>
</annotationProcessorPaths>
</configuration>
</execution>
If you need to use Lombok classes in Kotlin code, you need to use delombok:
<plugin>
<groupId>org.projectlombok</groupId>
<artifactId>lombok-maven-plugin</artifactId>
<version>${lombok.version}.0</version>
<executions>
<execution>
<id>delombok</id>
<phase>generate-sources</phase>
<goals>
<goal>delombok</goal>
</goals>
<configuration>
<formatPreferences>
<javaLangAsFQN>skip</javaLangAsFQN>
</formatPreferences>
<verbose>true</verbose>
</configuration>
</execution>
<execution>
<id>test-delombok</id>
<phase>generate-test-sources</phase>
<goals>
<goal>testDelombok</goal>
</goals>
<configuration>
<verbose>true</verbose>
</configuration>
</execution>
</executions>
</plugin>
In this case you don't need kapt at all. Works like a charm for me.

Answer 2

after lots of googling, i came up with this solution which allows lombok-enhanced java and kotlin code in the same module to call each other:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.ericytsang</groupId>
<artifactId>playground</artifactId>
<version>1.0-SNAPSHOT</version>
<packaging>jar</packaging>
<name>com.ericytsang playground</name>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<kotlin.version>1.2.50</kotlin.version>
<junit.version>4.12</junit.version>
<lombok.version>1.16.8</lombok.version>
</properties>
<dependencies>
<dependency>
<groupId>org.jetbrains.kotlin</groupId>
<artifactId>kotlin-stdlib</artifactId>
<version>${kotlin.version}</version>
</dependency>
<dependency>
<groupId>org.jetbrains.kotlin</groupId>
<artifactId>kotlin-test-junit</artifactId>
<version>${kotlin.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>${junit.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
<version>${lombok.version}</version>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.projectlombok</groupId>
<artifactId>lombok-maven-plugin</artifactId>
<version>${lombok.version}.0</version>
<executions>
<execution>
<id>delombok</id>
<phase>generate-sources</phase>
<goals>
<goal>delombok</goal>
</goals>
<configuration>
<sourceDirectory>src/main/java</sourceDirectory>
<outputDirectory>${project.build.directory}/delombok-main</outputDirectory>
<addOutputDirectory>false</addOutputDirectory>
</configuration>
</execution>
<execution>
<id>delombok-test</id>
<phase>generate-test-sources</phase>
<goals>
<goal>delombok</goal>
</goals>
<configuration>
<sourceDirectory>src/test/java</sourceDirectory>
<outputDirectory>${project.build.directory}/delombok-test</outputDirectory>
<addOutputDirectory>false</addOutputDirectory>
</configuration>
</execution>
</executions>
</plugin>
<plugin>
<groupId>org.jetbrains.kotlin</groupId>
<artifactId>kotlin-maven-plugin</artifactId>
<version>${kotlin.version}</version>
<executions>
<execution>
<id>compile</id>
<phase>process-sources</phase>
<goals>
<goal>compile</goal>
</goals>
<configuration>
<sourceDirs>${project.build.directory}/delombok-main</sourceDirs>
</configuration>
</execution>
<execution>
<id>test-compile</id>
<phase>test-compile</phase>
<goals>
<goal>test-compile</goal>
</goals>
<configuration>
<sourceDirs>${project.build.directory}/delombok-test</sourceDirs>
</configuration>
</execution>
</executions>
</plugin>
</plugins>
</build>
</project>
after implementing this solution, i revised it multiple times.
i want to keep my source code in src/main/java instead of src/main/lombok, so i added the <sourceDirectory>src/main/java</sourceDirectory> elements in the lombok configurations.
adding the above configurations caused duplicate class compile errors because the compiler was compiling the delomboked code as well as the code in src/main/java...i only want it to compile the delomboked code...but i also want the IDE to ignore the delomboked code....so i added <addOutputDirectory>false</addOutputDirectory> to lombok plugin, and <sourceDirs>${project.build.directory}/delombok-main</sourceDirs> to the kotlin plugin.
helpful discussion on delomboking code