targetDbClusterIdentifier
The identifier of the secondary Amazon DocumentDB cluster to promote to the new primary for the global database 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-:._]*