callerReference property
A value that you specify to uniquely identify an invalidation request.
CloudFront uses the value to prevent you from accidentally resubmitting an
identical request. Whenever you create a new invalidation request, you must
specify a new value for CallerReference and change other values
in the request as applicable. One way to ensure that the value of
CallerReference is unique is to use a timestamp,
for example, 20120301090000.
If you make a second invalidation request with the same value for
CallerReference, and if the rest of the request is the same,
CloudFront doesn't create a new invalidation request. Instead, CloudFront
returns information about the invalidation request that you previously
created with the same CallerReference.
If CallerReference is a value you already sent in a previous
invalidation batch request but the content of any Path is
different from the original request, CloudFront returns an
InvalidationBatchAlreadyExists error.
Implementation
final String callerReference;