code: @Override
      public ListGatewaysResult listGateways(ListGatewaysRequest request) {
          request = beforeClientExecution(request);
          return executeListGateways(request);
      }
docs: <p>
  Retrieves a list of gateway summaries. Use GetGateway to retrieve details of a specific gateway. An optional
  gateway group ARN can be provided to only retrieve gateway summaries of gateways that are associated with that
  gateway group ARN.
  </p>
  
  @param listGatewaysRequest
  @return Result of the ListGateways operation returned by the service.
  @sample AmazonAlexaForBusiness.ListGateways
  @see <a href="http://docs.aws.amazon.com/goto/WebAPI/alexaforbusiness-2017-11-09/ListGateways" target="_top">AWS
  API Documentation</a>