refundexternaltransaction method
      
Future<ExternalTransaction> 
refundexternaltransaction(
    
- RefundExternalTransactionRequest request,
 - String name, {
 - String? $fields,
 
Refunds or partially refunds an existing external transaction.
request - The metadata request object.
Request parameters:
name - Required. The name of the external transaction that will be
refunded. Format:
applications/{package_name}/externalTransactions/{external_transaction}
Value must have pattern
^applications/\[^/\]+/externalTransactions/\[^/\]+$.
$fields - Selector specifying which fields to include in a partial
response.
Completes with a ExternalTransaction.
Completes with a commons.ApiRequestError if the API endpoint returned an error.
If the used http.Client completes with an error when making a REST call,
this method will complete with the same error.
Implementation
async.Future<ExternalTransaction> refundexternaltransaction(
  RefundExternalTransactionRequest request,
  core.String name, {
  core.String? $fields,
}) async {
  final body_ = convert.json.encode(request);
  final queryParams_ = <core.String, core.List<core.String>>{
    if ($fields != null) 'fields': [$fields],
  };
  final url_ =
      'androidpublisher/v3/' + core.Uri.encodeFull('$name') + ':refund';
  final response_ = await _requester.request(
    url_,
    'POST',
    body: body_,
    queryParams: queryParams_,
  );
  return ExternalTransaction.fromJson(
    response_ as core.Map<core.String, core.dynamic>,
  );
}