Spock Test of a simple request to the GitHub api that fails for HttpBuilder but works via the URL.text

GitHubApiTest

package com.qmetric.renewal.githubapi

import groovy.json.JsonSlurper
import groovyx.net.http.HTTPBuilder
import groovyx.net.http.RESTClient
import spock.lang.Specification

import static groovyx.net.http.ContentType.JSON

class GitHubApiTest extends Specification
{
    public static final String GITHUB_API = 'https://api.github.com'
    public static final String USER_PATH = '/users/xan'

    def 'access git-hub web api via HTTPBuilder'()
    {
        def http = new HTTPBuilder(GITHUB_API)
        when:
        def user = http.get(path: USER_PATH, contentType: JSON)
        then:
        user.login == 'xan'
    }

    def 'access git-hub web api via RESTClient'()
    {
        def http = new RESTClient(GITHUB_API)
        when:
        def user = http.get(path: USER_PATH, contentType: JSON)
        then:
        user.login == 'xan'
    }

    def 'access git-hub web api via JsonSlurper'()
    {
        when:
        def json = "${GITHUB_API}${USER_PATH}".toURL().text
        def user = new JsonSlurper().parseText(json)
        then:
        user.login == 'xan'
    }
}