public async Task ExchangeTokenAsync()

in wwauth/Google.Solutions.WWAuth/Adapters/StsAdapter.cs [91:142]
44 lines of code
2 McCabe index (conditional complexity)

        public async Task<TokenResponse> ExchangeTokenAsync(
            ISubjectToken externalToken,
            IList<string> scopes,
            CancellationToken cancellationToken)
        {
            try
            {
                this.logger.Info(
                    "Exchanging token for audience '{0}'",
                    this.Audience);

                using (var service = CreateService())
                {
                    var response = await service.V1
                        .Token(
                            new GoogleIdentityStsV1ExchangeTokenRequest()
                            {
                                Audience = this.Audience,
                                GrantType = "urn:ietf:params:oauth:grant-type:token-exchange",
                                RequestedTokenType = "urn:ietf:params:oauth:token-type:access_token",
                                Scope = string.Join(" ", scopes),
                                SubjectTokenType = externalToken.Type.GetDescription(),
                                SubjectToken = externalToken.Value,
                            })
                        .WithCredentials<
                            Google.Apis.CloudSecurityToken.v1.V1Resource.TokenRequest, 
                            GoogleIdentityStsV1ExchangeTokenResponse>(this.clientSecrets)
                        .ExecuteAsync(cancellationToken)
                        .ConfigureAwait(false);

                    this.logger.Info("Successfully exchanged token");

                    return new TokenResponse()
                    {
                        AccessToken = response.AccessToken,
                        ExpiresInSeconds = response.ExpiresIn,
                        TokenType = response.TokenType
                    };
                }
            }
            catch (GoogleApiException e)
            {
                //
                // Try to convert the exception.
                //
                var tokenException = TokenExchangeException.FromApiException(e);

                this.logger.Error(tokenException, "{0}", tokenException.Message);

                throw tokenException;
            }
        }