@NotNull
  private static List<StandardMethodContract> boxReturnValues(List<StandardMethodContract> contracts) {
    return ContainerUtil.mapNotNull(contracts, contract -> {
      if (contract.getReturnValue().isBoolean()) {
        return contract.withReturnValue(ContractReturnValue.returnNotNull());
      }
      return contract;
    });
  }
@NotNull
  private static List<StandardMethodContract> boxReturnValues(List<StandardMethodContract> contracts)