Manually wait for JitPack to make an artifact available

wait-jitpack.gradle

def waitJitpack(group, module, hash) {
    preBuild.dependsOn(tasks.create(name: "waitJitpack-${module}-${hash}") { thisTask ->
        def url = "https://jitpack.io/${group.replace('.', '/')}/${module}/${hash}/${module}-${hash}.pom"

        def backoffLimit = 7
        for (def backoffCount : (0..backoffLimit)) {
            def connection = new URL(url).openConnection() as HttpURLConnection

            def timeout = (2**backoffCount) * 5 * 1000; // exponential timeout
            connection.setConnectTimeout(timeout)
            connection.setReadTimeout(timeout)

            connection.setRequestMethod("HEAD");
            connection.setInstanceFollowRedirects(true)

            try {
                def responseCode = connection.getResponseCode();
                if (responseCode >= 200 && responseCode <= 299) {
                    // success. Just bail
                    return
                } else {
                    def responseMessage = connection.getResponseCode();
                    throw new RuntimeException("Failed reaching Jitpack for ${group}:${module}:${hash}: ${responseMessage}")
                }
            } catch (SocketTimeoutException ignored) {
                if (backoffCount == backoffLimit) {
                    throw new Exception("Exhausted waiting for Jipack on ${group}:${module}:${hash}")
                }

                println "Retrying JitPack ${backoffCount+1}/${backoffLimit+1} for ${group}:${module}:${hash}"
            } catch (Exception e) {
                throw e
            }
        }
    })

    return "${group}:${module}:${hash}"
}

ext {
    waitJitpack = this.&waitJitpack
}