private static boolean isSuperValue(DfaValue superValue, DfaValue subValue) {
    if (DfaTypeValue.isUnknown(superValue) || superValue == subValue) return true;
    if (superValue instanceof DfaTypeValue && subValue instanceof DfaTypeValue) {
      return superValue.getDfType().isMergeable(subValue.getDfType());
    }
    return false;
  }
private static boolean isSuperValue(DfaValue superValue, DfaValue subValue)