code: @SuppressWarnings("unchecked")
      public Map<String, String> getHashes(Algorithms alg) {
          String key = normalizeKey(alg);
          if (hashes.containsKey(key)) {
              Record record = hashes.get(key);
              if (record.containsKey(FieldName.FILE_HASHES)) {
                  return (Map<String, String>) record.get(FieldName.FILE_HASHES);
              }
          }
          return new HashMap<String, String>();
      }
docs: Return a map of {fingerprint:file} of the contents (if any) for the given
  algorithm.
  
  @param alg
  @return