code: @Override
      public UpdateSubnetGroupResult updateSubnetGroup(UpdateSubnetGroupRequest request) {
          request = beforeClientExecution(request);
          return executeUpdateSubnetGroup(request);
      }
docs: <p>
  Modifies an existing subnet group.
  </p>
  
  @param updateSubnetGroupRequest
  @return Result of the UpdateSubnetGroup operation returned by the service.
  @throws SubnetGroupNotFoundException
  The requested subnet group name does not refer to an existing subnet group.
  @throws SubnetQuotaExceededException
  The request cannot be processed because it would exceed the allowed number of subnets in a subnet group.
  @throws SubnetInUseException
  The requested subnet is being used by another subnet group.
  @throws InvalidSubnetException
  An invalid subnet identifier was specified.
  @throws ServiceLinkedRoleNotFoundException
  @sample AmazonDax.UpdateSubnetGroup
  @see <a href="http://docs.aws.amazon.com/goto/WebAPI/dax-2017-04-19/UpdateSubnetGroup" target="_top">AWS API
  Documentation</a>