Gradle instruction for renaming apk with app version

build.gradle

applicationVariants.all { variant ->
        variant.outputs.each { output ->
            def outputFile = output.outputFile
            if (outputFile != null && outputFile.name.endsWith('.apk')) {
                def version = defaultConfig.versionName
                //version = version.replaceAll('\\.', '_')
                def fileName = "appName_v" + version + ".apk"
                if(variant.name.equals("variantName")){
                    fileName = "appName_variant_v" + version + ".apk"
                }
                output.outputFile = new File(outputFile.parent, fileName)
            }
        }
    }