code: @Override
      public StartMonitoringMembersResult startMonitoringMembers(StartMonitoringMembersRequest request) {
          request = beforeClientExecution(request);
          return executeStartMonitoringMembers(request);
      }
docs: Re-enables GuardDuty to monitor findings of the member accounts specified by the account IDs. A master GuardDuty
  account can run this command after disabling GuardDuty from monitoring these members' findings by running
  StopMonitoringMembers.
  
  @param startMonitoringMembersRequest
  StartMonitoringMembers request body.
  @return Result of the StartMonitoringMembers operation returned by the service.
  @throws BadRequestException
  400 response
  @throws InternalServerErrorException
  500 response
  @sample AmazonGuardDuty.StartMonitoringMembers
  @see <a href="http://docs.aws.amazon.com/goto/WebAPI/guardduty-2017-11-28/StartMonitoringMembers"
  target="_top">AWS API Documentation</a>