IntelliJ IDEA Gradle Java Swing form compilation (build.gradle)

build.gradle

apply plugin: 'java'
apply plugin: 'application'

group 'nl.hypothermic'
version '7.1.90144-RELEASE'

mainClassName = 'nl.hypothermic.xanalyzer.modules.md-main.Main'

sourceCompatibility = 1.7

configurations {
    antTask
}

repositories {
    mavenCentral()
}

dependencies {
    testCompile group: 'junit', name: 'junit', version: '4.11'
    antTask 'com.intellij:forms_rt:7.0.3'
    antTask group: 'com.intellij', name: 'javac2', version: '7.0.3'
}

task compileJava(overwrite: true, dependsOn: configurations.compile.getTaskDependencyFromProjectDependency(true, 'jar')) {
    doLast {
        project.sourceSets.main.output.classesDir.mkdirs()
        ant.taskdef name: 'javac2', classname: 'com.intellij.ant.Javac2', classpath: configurations.antTask.asPath
        ant.javac2 srcdir: project.sourceSets.main.java.srcDirs.join(':'),
            classpath: project.sourceSets.main.compileClasspath.asPath,
            destdir: project.sourceSets.main.output.classesDir,
            source: sourceCompatibility,
            target: targetCompatibility,
            includeAntRuntime: false
    }
}