URL queryUrl =
    new URL(SERVICE_URL + "/feeds/features/" + MAPID + "/full");

GoogleService myService = new MapsService("exampleCo-exampleApp-1");
myService.setUserCredentials(USERNAME, PASSWORD);

FeatureFeed feed = myService.getFeed(queryUrl, FeatureFeed.class);

for (FeatureEntry entry : feed.getEntries()) {
   XmlBlob xml = ((OtherContent)entry.getContent()).getXml();
   xml.setBlob(xml.getBlob().replaceAll(
     "(<Icon>\\s*<href>)[^<]*", "$1" + NEW_ICON));
   myService.update(new URL(entry.getEditLink().getHref()), entry);
}