callerReference property
A unique value (for example, a date-time stamp) that ensures that the request can't be replayed.
If the value of CallerReference is new (regardless of the
content of the DistributionConfig object), CloudFront creates a
new distribution.
If CallerReference is a value that you already sent in a
previous request to create a distribution, CloudFront returns a
DistributionAlreadyExists error.
Implementation
final String callerReference;