kotlin-kapt

Maven tiles for Kotlin kapt (annotation processors)

Why

To simplify the configuration of the maven kotlin compiler plugin when using multiple annotation processors (KAPT).

Example

In maven build / plugins add:

<plugin>
<groupId>io.repaint.maven</groupId>
<artifactId>tiles-maven-plugin</artifactId>
<version>2.16</version>
<extensions>true</extensions>
<configuration>
  <tiles>
    <!-- kotlin compile with kapt support -->
    <tile>io.avaje.kapt:compile:1.1</tile>

    <!-- multiple annotation processors -->
    <tile>io.avaje.kapt:dinject-generator:1.15</tile>
    <tile>io.avaje.kapt:javalin-generator:1.15</tile>
    <tile>io.avaje.kapt:querybean-generator:12.1.5</tile>

    <!-- other tiles -->
    <tile>org.avaje.tile:lib-classpath:1.1</tile>
    <tile>io.ebean.tile:enhancement:12.1.5</tile>
  </tiles>
</configuration>
</plugin>

The tiles

compile tile

This tile that adds kotlin compiler and java compiler

kapt tiles - dinject-generator, javalin-generator, querybean-generator

These tiles specify the annotation processor to include with the kotlin compiler

Configuration

The default configuration properties this tile uses is:

• java.release -> 11
• kotlin.version -> 1.3.61
• kotlin.apiVersion -> 1.3
• kotlin.jvmTarget -> 11

Override these as needed in the pom properties section.

  <properties>
    <tile-merge-target>true</tile-merge-target>
    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    <java.release>11</java.release>
    <kotlin.version>1.3.61</kotlin.version>
    <kotlin.apiVersion>1.3</kotlin.apiVersion>
    <kotlin.jvmTarget>11</kotlin.jvmTarget>
    <maven-compiler-plugin.version>3.8.1</maven-compiler-plugin.version>
  </properties>

How this works

This relies on the io.repaint.maven tiles plugin version 2.16 (or greater). The tiles plugin has the feature where we can have tiles that effectively merge their configuration (for our use case merging the annotation processors into the kotlin compile plugin).

A tile can be defined as a tile-merge-target (our io.avaje.kapt:compile tile). This means that tile defines a tiles-append attribute specifying where other tiles can merge content into. In this case we are merging into annotationProcessorPaths.

Tiles can be defined as tile-merge-source meaning that they have their source merged into a target tile. For dinject-generator, javalin-generator and querybean-generator these tiles all supply content in annotationProcessorPaths that is merged into the io.avaje.kapt:compile tile.