Cacheable exec task

build.gradle

task webpack(type: Exec) {
    outputs.cacheIf { true }
    inputs.file("package-lock.json")
    inputs.dir("app")
    // NOTE: Add inputs.file("webpack.config.js") for projects that have it
    outputs.dir("$buildDir/js")

    commandLine "$projectDir/node_modules/.bin/webpack", "app/index.js", "$buildDir/js/bundle.js"
}