private Iterable<Image> listImages(String projectId) throws OpsException {
List<Image> ret = Lists.newArrayList();
ImageList imageList;
try {
log.debug("Listing images in project " + projectId);
imageList = compute.images().list(projectId).execute();
} catch (IOException e) {
throw new OpsException("Error listing images", e);
}
if (imageList.getItems() != null) {
ret.addAll(imageList.getItems());
}
return ret;
}