Groovy RestClient GET; JIRA API

How to create a Rest client to

       

import groovyx.net.http.RESTClient;
import groovyx.net.http.HttpResponseDecorator;
import org.apache.http.HttpRequest;
import org.apache.http.protocol.HttpContext;
import org.apache.http.HttpRequestInterceptor;
import groovy.json.JsonSlurper;
import static groovyx.net.http.Method.*
import static groovyx.net.http.ContentType.*

@Grapes([
@Grab(group = 'org.codehaus.groovy.modules.http-builder', 
      module = 'http-builder', version = '0.5.1'),
@GrabExclude('org.codehaus.groovy:groovy')
])



def jiraApiUrl = 'http://localhost:8989/rest/api/2/'
def jiraClient = new RESTClient(jiraApiUrl)
def basic = 'Basic ' + 
'user:password'.bytes.encodeBase64().toString()
jiraClient.client.addRequestInterceptor(
  new HttpRequestInterceptor() {
    void process(HttpRequest httpRequest, 
                 HttpContext httpContext) {
      httpRequest.addHeader('Authorization', basic)
  }
})

def serverInfo = jiraClient.get(path: 'issue/SPACE-4')
println serverInfo.data

def slurp = 
  new JsonSlurper().parseText(serverInfo.data.toString())
  
  println slurp.fields.description