The Amazon Resource Name (ARN) of the runtime role for a step on the cluster. The
runtime role can be a cross-account IAM role. The runtime role ARN is a combination of
account ID, role name, and role type using the following format:
arn:aws:iam::1234567890:role/ReadOnly is a correctly formatted
runtime role ARN.
A list of StepConfig to be executed by the job flow.