The AWS documentation tells us the following:
```
--replication-group-id (string)
The replication group identifier. This parameter is stored as a
lowercase string.
Constraints:
A name must contain from *1 to 20* alphanumeric characters or hyphens.
The first character must be a letter.
A name cannot end with a hyphen or contain two consecutive hyphens.
```
This is not correct and is causing users errors:
```
* aws_elasticache_replication_group.bar: Error creating Elasticache
* Replication Group: InvalidParameterValue: Replication group id should
* be no more than 16 characters.
status code: 400, request id:
```
Tuning the Validation from 20 to 16 characters to avoid user issues