private Instance describeInstance(AmazonEC2Client ec2, String ec2InstanceId) {
Instance ec2Instance = null;
{
DescribeInstancesRequest request = new DescribeInstancesRequest();
request.setInstanceIds(Collections.singletonList(ec2InstanceId));
DescribeInstancesResult response = ec2.describeInstances(request);
List<Reservation> reservations = response.getReservations();
for (Reservation reservation : reservations) {
for (Instance i : reservation.getInstances()) {
if (ec2Instance != null) {
throw new IllegalStateException();
}