code: private DescribeSubnetsResponseType describeSubnets() {
          DescribeSubnetsResponseType ret = new DescribeSubnetsResponseType();
          ret.setRequestId(UUID.randomUUID().toString());
          SubnetSetType subnetSetType = new SubnetSetType();
  
          for (Iterator<MockSubnet> mockSubnet = mockSubnetController.describeSubnets()
                  .iterator(); mockSubnet.hasNext();) {
              MockSubnet item = mockSubnet.next();
              SubnetType subnetType = new SubnetType();
              if (!DEFAULT_MOCK_PLACEMENT.getAvailabilityZone().equals(currentRegion)) {
                  subnetType.setVpcId(currentRegion + "_" + item.getVpcId());
                  subnetType.setSubnetId(currentRegion + "_" + item.getSubnetId());
              } else {
                  subnetType.setVpcId(item.getVpcId());
                  subnetType.setSubnetId(item.getSubnetId());
              }
              subnetType.setSubnetId(item.getSubnetId());
              subnetType.setState("available");
              subnetType.setCidrBlock(item.getCidrBlock());
              subnetType.setAvailableIpAddressCount(item.getAvailableIpAddressCount());
              subnetType.setAvailabilityZone(currentRegion);
              subnetType.setDefaultForAz(false);
              subnetType.setMapPublicIpOnLaunch(false);
  
              subnetSetType.getItem().add(subnetType);
          }
  
          ret.setSubnetSet(subnetSetType);
  
          return ret;
      }
docs: Handles "describeSubnets" request and returns response with a subnet Set.
  
  @return a DescribeSubnetsResponseType with Created Vpcs