// following ways:
//
// - RoleARN - if a role-arn is specified in the request, the STS credential's
// policy is the role's policy.
//
// - inherited from parent - this is the case for AssumeRole API, where the
// parent user is an actual real user with their own (permanent) credentials and
// policy association.
//
// - inherited from "virtual" parent - this is the case for AssumeRoleWithLDAP