copySourceIfUnmodifiedSince
Copies the object if it hasn't been modified since the specified time.
If both the x-amz-copy-source-if-match
and x-amz-copy-source-if-unmodified-since
headers are present in the request and evaluate as follows, Amazon S3 returns 200 OK
and copies the data:
x-amz-copy-source-if-match
condition evaluates to truex-amz-copy-source-if-unmodified-since
condition evaluates to false