docs: @Override
      protected void printLine(State state, Writer pw, String externalForm, String hash) throws IOException {
          PrefixState prefixState = (PrefixState) state;
          int ix = externalForm.lastIndexOf('/');
          String prefix = externalForm.substring(0, ix);
          String name = externalForm.substring(ix);
          // If new prefix, print it.
          if (!prefix.equals(prefixState.lastPrefix)) {
              prefixState.lastPrefix = prefix;
              printPrefix(pw, prefix);
              pw.write('\n');
          }
          printName(pw, name);
          pw.write(SEPARATOR);
          pw.write(hash);
          pw.write('\n');
      }