Gradle task for uploading builds to TestFlight using HTTPBuilder

gistfile1.groovy

task uploadTf(dependsOn: assembleRelease) << {
    def teamToken = '<TestFlight team token here>'
    def apiToken = '<TestFlight api token here>'
    def lists = '<TestFlight distribution lists here>'
    def apk = file("build/apk/$project.name-release.apk")
    def notes = new File(file('changelog.mdown')).getText("UTF-8")
    def http = new HTTPBuilder('http://testflightapp.com')
    println('Uploading build to TestFlight...')
    http.request(POST, JSON) { req ->
        uri.path = '/api/builds.json'
        requestContentType = 'multipart/form-data'
        MultipartEntity entity = new MultipartEntity(HttpMultipartMode.BROWSER_COMPATIBLE)
        entity.addPart('distribution_lists', new StringBody(lists))
        entity.addPart('team_token', new StringBody(teamToken))    
        entity.addPart('api_token', new StringBody(apiToken))
        entity.addPart('notes', new StringBody(notes))
        entity.addPart('file', new FileBody(apk))
        req.setEntity(entity)
        response.success = {resp, json ->
            println("Upload successful!")
        }

        response.failure = {resp ->
            println(resp)
            throw new StopExecutionException("TestFlight upload failed! See server response above")
        }
    }
}