copySourceIfNoneMatch

Copies the object if its entity tag (ETag) is different than the specified ETag.

If both of the x-amz-copy-source-if-none-match and x-amz-copy-source-if-modified-since headers are present in the request as follows:

x-amz-copy-source-if-none-match condition evaluates to false, and;

x-amz-copy-source-if-modified-since condition evaluates to true;

Amazon S3 returns 412 Precondition Failed response code.