Provisioning reserved nodes for elasticache redis

Hi,

Apologies if this is in the AWS provider documentation but I could not find it.

I’m trying to provision ElastiCache redis nodes with the tf AWS provider and I’d like to get reserved nodes on a one year contract rather than on-demand.
I’m not seeing any properties in the documentation for the aws_elasticache_replication_group or the aws_elasticache_cluster.

Is this possible to do and if so can you please point me to the instructions for doing it? I looked at the default parameter groups AWS has and they don’t appear to support parameters that match the ElastiCache API settings for reserving an instance.

Thanks in advance