class Aws::S3::Plugins::IADRegionalEndpoint

def self.resolve_iad_regional_endpoint(cfg)
  default_mode_value =
    if cfg.respond_to?(:defaults_mode_config_resolver)
      cfg.defaults_mode_config_resolver.resolve(:s3_us_east_1_regional_endpoint)
    end
  mode = ENV['AWS_S3_US_EAST_1_REGIONAL_ENDPOINT'] ||
    Aws.shared_config.s3_us_east_1_regional_endpoint(profile: cfg.profile) ||
    default_mode_value ||
    'legacy'
  mode = mode.downcase
  unless %w(legacy regional).include?(mode)
    raise ArgumentError, "expected :s3_us_east_1_regional_endpoint or"\
      " ENV['AWS_S3_US_EAST_1_REGIONAL_ENDPOINT'] to be `legacy` or"\
      " `regional`."
  end
  mode
end