@SuppressWarnings("ConstantConditions")
  private void validateNatParams() {
    if (natMethod.equals(NatMethod.AUTO) && !unstableNatOptions.getNatMethodFallbackEnabled()) {
      throw new ParameterException(
          this.commandLine,
          "The `--Xnat-method-fallback-enabled` parameter cannot be used in AUTO mode. Either remove --Xnat-method-fallback-enabled"
              + " or select another mode (via --nat--method=XXXX)");
    }
  }
Returns a network interface checker that can be used to validate P2P options.

@return A {@link P2PDiscoveryOptions.NetworkInterfaceChecker} that checks if a network
    interface is available.
app/src/main/java/org/hyperledger/besu/cli/BesuCommand.java