code: public static String compareChecksum(StorageProvider provider,
                                           String spaceId,
                                           String contentId,
                                           String checksum)
          throws StorageException {
          String providerChecksum =
              provider.getContentProperties(spaceId, contentId).
                  get(StorageProvider.PROPERTIES_CONTENT_CHECKSUM);
          return compareChecksum(providerChecksum, spaceId, contentId, checksum);
      }
docs: Determines if the checksum for a particular piece of content
  stored in a StorageProvider matches the expected checksum value.
  
  @param provider  The StorageProvider where the content was stored
  @param spaceId   The Space in which the content was stored
  @param contentId The Id of the content
  @param checksum  The content checksum, either provided or computed
  @throws StorageException if the included checksum does not match
  the storage provider generated checksum
  @returns the validated checksum value from the provider