docs: protected final int getIntegerIndex(SoyValue key) {
      if (key instanceof StringData) {
        try {
          // TODO(gboyer): Remove this case as non-compliant code is fixed. However, since this works
          // in Javascript, it is particularly difficult to fix callers.  (internal) b/11416037
          return Integer.parseInt(key.stringValue());
        } catch (IllegalArgumentException e) {
          throw new SoyDataException("\"" + key + "\" is not a valid list index (must be an int)");
        }
      } else {
        return key.integerValue();
      }
    }