targetDbClusterIdentifier
The identifier of the secondary Amazon DocumentDB cluster that you want to promote to the primary for the global cluster. Use the Amazon Resource Name (ARN) for the identifier so that Amazon DocumentDB can locate the cluster in its Amazon Web Services region.
Constraints:
Must match the identifier of an existing secondary cluster.
Minimum length of 1. Maximum length of 255.
Pattern: [A-Za-z][0-9A-Za-z-:._]*