checkState(isConfigured(), "attempt to use unconfigured ScalingGroup");
try {
List<Server> servers = this.client.getServers(
Constants.SCALING_GROUP_TAG, getScalingGroupName());
return transform(servers, new ServerToMachine());
} catch (Exception e) {
throw new ScalingGroupException(format(
"failed to retrieve machines in scaling group \"%s\": %s",
this.scalingGroupName, e.getMessage()), e);
}