code: public void restoreAllInternetGateway(final Collection<MockInternetGateway> internetGateways) {
          allMockInternetGateways.clear();
          if (null != internetGateways) {
              for (MockInternetGateway instance : internetGateways) {
                  allMockInternetGateways.put(instance.getInternetGatewayId(), instance);
              }
          }
      }
docs: Clear {@link #allMockInternetGateways} and restore it from given a collection of instances.
  
  @param internetGateways
  collection of MockInternetGateway to restore