Amazon.SecurityToken.SAML.SAMLAssertion.GetRoleCredentials C# (CSharp) Method

        public SAMLImmutableCredentials GetRoleCredentials(IAmazonSecurityTokenService stsClient, string principalAndRoleArns, TimeSpan duration)
        {
            string roleArn = null;
            string principalArn = null;

            foreach (var s in RoleSet.Values)
            {
                if (s.Equals(principalAndRoleArns, StringComparison.OrdinalIgnoreCase))
                {
                    var roleComponents = s.Split(',');
                    principalArn = roleComponents.First();
                    roleArn = roleComponents.Last();
                    break;
                }
            }

            if (string.IsNullOrEmpty(roleArn) || string.IsNullOrEmpty(principalArn))
                throw new ArgumentException("Unknown or invalid role specified.");

            var response = stsClient.AssumeRoleWithSAML(new AssumeRoleWithSAMLRequest
            {
                SAMLAssertion = AssertionDocument,
                RoleArn = roleArn,
                PrincipalArn = principalArn,
                DurationSeconds = (int)duration.TotalSeconds
            });

            return new SAMLImmutableCredentials(response.Credentials.GetCredentials(), 
                                                response.Credentials.Expiration.ToUniversalTime(),
                                                response.Subject);
        }