fix: store final checksum on CompleteMultipartUpload

Previously, if no object checksum type/algorithm was specified when initiating a multipart upload, the CompleteMultipartUpload request would compute the final object’s CRC64NVME checksum but not persist it. This logic has now been fixed, and in the scenario described above the checksum is stored on the final object. There should no longer be any case where a CompleteMultipartUpload request finishes without persisting the final object checksum.

tests/integration/CompleteMultipartUpload.go

@@ -1111,6 +1111,24 @@ func CompleteMultipartUpload_should_ignore_the_final_checksum(s *S3Conf) error {
 			return fmt.Errorf("expected non nil crc64nvme checksum")
 		}
 
+		ctx, cancel = context.WithTimeout(context.Background(), shortTimeout)
+		out, err := s3client.HeadObject(ctx, &s3.HeadObjectInput{
+			Bucket:       &bucket,
+			Key:          &obj,
+			ChecksumMode: types.ChecksumModeEnabled,
+		})
+		cancel()
+		if err != nil {
+			return err
+		}
+
+		if out.ChecksumType != types.ChecksumTypeFullObject {
+			return fmt.Errorf("expected the final object checksum type to be %s, instead got %s", types.ChecksumTypeFullObject, out.ChecksumType)
+		}
+		if out.ChecksumCRC64NVME == nil {
+			return fmt.Errorf("expected non nil crc64nvme checksum")
+		}
+
 		return nil
 	})
 }