docs: public void migrateUnusedMetadataToTags() throws BinaryStoreException {
          for (S3ObjectSummary s : S3Objects.inBucket(s3Client, bucketName)) {
              String k = s.getKey();
              ObjectMetadata metadata = s3Client.getObjectMetadata(bucketName, k);
              String unused = metadata.getUserMetaDataOf(UNUSED_KEY);
              if (unused != null) {
                  setS3ObjectTag(k, UNUSED_TAG_KEY, unused);
                  setS3ObjectUserProperty(k, UNUSED_KEY, null);
              }
          }
      }