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 you already sent in a previous
request to create a distribution, and if the content of the
DistributionConfig is identical to the original request
(ignoring white space), CloudFront returns the same the response that it
returned to the original request.
If CallerReference is a value you already sent in a previous
request to create a distribution but the content of the
DistributionConfig is different from the original request,
CloudFront returns a DistributionAlreadyExists error.
Implementation
final String callerReference;