protected Content doGetContent(ContentItem contentItem) {
   try {
     return contentStore.getContent(contentItem.getSpaceId(), contentItem.getContentId());
   } catch (ContentStoreException e) {
     throw new RuntimeException(
         "Unable to get content for " + contentItem.toString() + " due to: " + e.getMessage());
   }
 }
 @Override
 public Map<String, String> getSourceProperties(ContentItem contentItem) {
   try {
     Map<String, String> properties =
         contentStore.getContentProperties(contentItem.getSpaceId(), contentItem.getContentId());
     return properties;
   } catch (ContentStoreException e) {
     throw new RuntimeException(
         "Unable to get checksum for " + contentItem.toString() + " due to: " + e.getMessage());
   }
 }