AndroidStudio, Gradle, apk name debug/release

android {
...

    buildTypes {

        debug {
...

        }

        release {
...

        }

        applicationVariants.all { variant ->
            variant.outputs.each { output ->

                def apkName = ""                def formattedDate = new Date().format('yyyyMMdd')

                if (variant.buildType.name == "release"){
                    apkName = "AppName_" + variant.versionName + "_" + formattedDate + ".apk"                }else{
                    apkName = "AppName_dev" + variant.versionName + "_" + formattedDate + ".apk"                }
                output.outputFile = new File(output.outputFile.parent, apkName)
            }
        }

}