gradle slack file upload task

def createSlackTasks() {
        mAndroidAppExtension.applicationVariants.all{
            if (!it.buildType.debuggable){
                def task = mProject.tasks.create("slack${it.name.capitalize()}", UploadSlackTask)
                task.variant = it
                task.dependsOn it.assemble
            }
        }
}

class UploadSlackTask extends DefaultTask {
    @Input
    ApplicationVariant variant;

    @TaskAction
    def upload(){
        File apkFile  = variant.outputs[0].outputFile
        def http = new HTTPBuilder("https://slack.com/api/files.upload")
        http.request(Method.POST) { req ->
            requestContentType: "multipart/form-data"
            MultipartEntity multiPartContent = new MultipartEntity(HttpMultipartMode.BROWSER_COMPATIBLE)
            multiPartContent.addPart("channels", new StringBody("android"))
            multiPartContent.addPart("token", new StringBody("xoxp-"))
            multiPartContent.addPart("file", new FileBody(apkFile))
            req.setEntity(multiPartContent)
            response.success = { resp, reader ->
                if (resp.statusLine.statusCode == 200) {
                    println(reader.getText())
                }
            }
        }
    }
}

Hello,
could you provide a complete example ?
I can not integrate it in my script .
Thanks Ivan