ClientLogin from an appengine app to another appengine app

GAEClientLogin.java

package fr.salvadordiaz.gae.gwt.server;

import static com.google.appengine.api.urlfetch.FetchOptions.Builder.*;
import static com.google.common.collect.Iterables.*;
import static com.google.common.collect.Maps.*;

import java.io.IOException;
import java.net.URL;
import java.util.Map;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.google.appengine.api.urlfetch.HTTPHeader;
import com.google.appengine.api.urlfetch.HTTPMethod;
import com.google.appengine.api.urlfetch.HTTPRequest;
import com.google.appengine.api.urlfetch.HTTPResponse;
import com.google.appengine.api.urlfetch.URLFetchService;
import com.google.appengine.api.urlfetch.URLFetchServiceFactory;
import com.google.common.base.Function;
import com.google.common.base.Joiner;
import com.google.common.base.Joiner.MapJoiner;
import com.google.common.base.Splitter;
import com.google.common.collect.ImmutableMap;

public class CronTask extends HttpServlet {
	private static final long serialVersionUID = 2939037941670085239L;

	private URLFetchService urlFetchService = URLFetchServiceFactory.getURLFetchService();

	private static final MapJoiner joiner = Joiner.on("&").withKeyValueSeparator("=");
	private static final Splitter lineSplitter = Splitter.on("\n").omitEmptyStrings().trimResults();
	private static final Splitter keyValueSplitter = Splitter.on("=").omitEmptyStrings().trimResults();
	private final Function<Iterable<String>, String> getValue = new Function<Iterable<String>, String>() {
		@Override
		public String apply(Iterable<String> input) {
			return get(input, 1, null);
		}
	};
	private final Function<Iterable<String>, String> getKey = new Function<Iterable<String>, String>() {
		@Override
		public String apply(Iterable<String> input) {
			return getFirst(input, null).toLowerCase();
		}

	};
	private final Function<String, Iterable<String>> splitKeyValue = new Function<String, Iterable<String>>() {
		@Override
		public Iterable<String> apply(String input) {
			return keyValueSplitter.split(input);
		}
	};
	private final Function<HTTPHeader, String> getHeaderName = new Function<HTTPHeader, String>() {
		@Override
		public String apply(HTTPHeader input) {
			return input.getName().toLowerCase();
		}
	};

	@Override
	protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
		//create the protected servlet request: use ClientLogin cookie
		final HTTPRequest sdcReq = new HTTPRequest(new URL("https://sdc-example.appspot.com/sdc/sdc"));
		sdcReq.addHeader(new HTTPHeader("Cookie", getCookie()));
		//make the call to the protected servlet which will fetch the SDC resource
		final HTTPResponse sdcResp = urlFetchService.fetch(sdcReq);
		//TODO: process the response
	}

	private String getCookie() throws IOException {
		//create token request with all the necessary parameters
		final HTTPRequest tokenReq = new HTTPRequest(new URL("https://www.google.com/accounts/ClientLogin"), HTTPMethod.POST);
		tokenReq.setPayload(joiner.join(ImmutableMap.<String, String> builder()//
				.put("Email", "****@mydomain.com")//
				.put("Passwd", "********")//
				.put("accountType", "HOSTED")//
				.put("service", "ah")//
				.put("source", "sdc-example.appspot.com").build()).getBytes());
		//make the request to fetch the token response
		final HTTPResponse tokenResp = urlFetchService.fetch(tokenReq);
		//process token response: split response in lines, then each line in key-value pairs and finally transform the key-value pairs to a map 
		final Iterable<Iterable<String>> split = transform(lineSplitter.split(new String(tokenResp.getContent())), splitKeyValue);
		final Map<String, String> tokenRespMap = transformValues(uniqueIndex(split, getKey), getValue);
		//create cookie request: the cookie we want will come in a 302 response (redirect) so we have to tell URLFetchService not to follow redirects
		final HTTPRequest cookieReq = new HTTPRequest(new URL("https://sdc-example.appspot.com/_ah/login?auth=" + tokenRespMap.get("auth")), HTTPMethod.GET,
				doNotFollowRedirects());
		//make the request to fetch cookie response
		final HTTPResponse cookieResp = urlFetchService.fetch(cookieReq);
		//process cookie response: index headers by their lowercase name and return the appropriate cookie
		final Map<String, HTTPHeader> headersByName = uniqueIndex(cookieResp.getHeaders(), getHeaderName);
		return headersByName.get("set-cookie").getValue();
	}
}