docs: @Override
      protected RegData parseLine(State state, String line) {
          PrefixState prefixState = (PrefixState) state;
          int sepIndex = line.indexOf(SEPARATOR);
          if (sepIndex == -1) {
              // We are on prefix line.
              prefixState.lastPrefix = loadPrefix(line);
              return null;
          } else {
              String urlExternalForm = prefixState.lastPrefix + loadName(line.substring(0, sepIndex));
              String hash = line.substring(sepIndex + SEPARATOR_LEN);
              return new RegData(urlExternalForm, hash);
          }
      }