How can I add a generated Source Folder to my Source Path in Gradle?

Question

I use annotation processing. Therefore I use the apt plugin. It generates new java sources in build/source/apt.

Here is my build.gradle:

apply plugin: 'java'
apply plugin: 'eclipse'
apply plugin: 'apt'
apply plugin: 'war'
apply plugin: 'gwt'
apply plugin: 'jetty'

sourceCompatibility = 1.7
version = '1.0'

eclipse {
    classpath {
       downloadSources=true
       downloadJavadoc=true
    }
}

buildscript {
    repositories {
        mavenCentral()
        jcenter()
        maven {
            url "https://oss.sonatype.org/content/repositories/snapshots/"
        }
    }
    dependencies {
        classpath 'de.richsource.gradle.plugins:gwt-gradle-plugin:0.6'      
        classpath 'com.jimdo.gradle:gradle-apt-plugin:0.5-SNAPSHOT'
    }
}

repositories {
    mavenCentral()
    maven {
        name = "sonatype"
        url = "https://oss.sonatype.org/content/repositories/snapshots/"
    }
}

dependencies {
    apt 'com.google.dagger:dagger-compiler:2.0-SNAPSHOT:jar-with-dependencies'

    compile 'com.google.guava:guava:18.0'
    compile 'com.google.guava:guava-gwt:18.0'
    compile 'javax.inject:javax.inject:1'   
    compile 'com.google.dagger:dagger:2.0-SNAPSHOT'
}

gwt {
    gwtVersion='2.7.0'
    logLevel = 'INFO'
    minHeapSize = "512M";
    maxHeapSize = "1024M";


    compiler {
        strict = true;
    }
    modules 'test.GWTT'     
}

tasks.withType(de.richsource.gradle.plugins.gwt.AbstractGwtActionTask) {
    args '-XjsInteropMode', 'JS'
}

I need this sources to be available in my project such that eclipse can find them and such that they are included while compiling the project how can I do that?

Edit: Using

sourceSets {
    apt{
        java{
            srcDir 'build/source/apt'
        }
    }
}

Leads to the following errors when running gradle build:

Compiling module test.GWTT
   Tracing compile failure path for type 'test.client.GWTT'
      [ERROR] Errors in 'file:/Users/mg/Documents/Grails/GGTS3.6.2/TestGradle2/src/main/java/test/client/GWTT.java'
         [ERROR] Line 17: No source code is available for type test.client.test2.Dagger_MyWidgetGinjector; did you forget to inherit a required module?
   Finding entry point classes
      Tracing compile failure path for type 'test.client.GWTT'
         [ERROR] Errors in 'file:/Users/mg/Documents/Grails/GGTS3.6.2/TestGradle2/src/main/java/test/client/GWTT.java'
            [ERROR] Line 17: No source code is available for type test.client.test2.Dagger_MyWidgetGinjector; did you forget to inherit a required module?
      [ERROR] Hint: Check the inheritance chain from your module; it may not be inheriting a required module or a module may not be adding its source path entries properly
:compileGwt FAILED

Using the former Eclipse finds the sources of the generated files but build does not.

Answer 1

sourceSets.main.java.srcDirs = ['build/generated-sources/xjc','src/main/java'] worked for me.