code: @Override
      public DescribeSubnetGroupsResult describeSubnetGroups(DescribeSubnetGroupsRequest request) {
          request = beforeClientExecution(request);
          return executeDescribeSubnetGroups(request);
      }
docs: <p>
  Returns a list of subnet group descriptions. If a subnet group name is specified, the list will contain only the
  description of that group.
  </p>
  
  @param describeSubnetGroupsRequest
  @return Result of the DescribeSubnetGroups operation returned by the service.
  @throws SubnetGroupNotFoundException
  The requested subnet group name does not refer to an existing subnet group.
  @throws ServiceLinkedRoleNotFoundException
  @sample AmazonDax.DescribeSubnetGroups
  @see <a href="http://docs.aws.amazon.com/goto/WebAPI/dax-2017-04-19/DescribeSubnetGroups" target="_top">AWS API
  Documentation</a>