When authenticating against AWS using credentials ...

# http4k

[darrenhobbs]

When authenticating against AWS using credentials from AssumeRole, there is a 3rd value 'sessionToken' that needs to be included. What's the best way to get this in? Add it to AwsCredentials as a nullable field? https://docs.aws.amazon.com/AmazonS3/latest/dev/RESTAuthentication.html#UsingTemporarySecurityCredentials