Dose OPC UA Method InputArguments can set default value?|OPC UA Implementation: Stacks, Tools, and Samples|Forum|OPC Foundation

My Code base on C#.

//Method Init
MethodState method = new MethodState(parent);
method.SymbolicName = name;
method.ReferenceTypeId = ReferenceTypeIds.HasComponent;
method.NodeId = new NodeId(path, NamespaceIndex);
method.BrowseName = new QualifiedName(path, NamespaceIndex);
method.DisplayName = new LocalizedText("en", name);
method.WriteMask = AttributeWriteMask.None;
method.UserWriteMask = AttributeWriteMask.None;
method.Executable = true;
method.UserExecutable = true;
//InputArguments Setup
method.InputArguments = new PropertyState<Argument[]>(method);
method.InputArguments.NodeId = new NodeId((string)method.NodeId.Identifier + @"\MethodsInputI", NamespaceIndex);
method.InputArguments.BrowseName = BrowseNames.InputArguments;
method.InputArguments.DisplayName = method.InputArguments.BrowseName.Name;
method.InputArguments.TypeDefinitionId = VariableTypeIds.PropertyType;
method.InputArguments.ReferenceTypeId = ReferenceTypeIds.HasProperty;
method.InputArguments.DataType = DataTypeIds.Argument;
method.InputArguments.ValueRank = ValueRanks.OneDimension;

//Value Setup
method.OutputArguments.Value = ValueInformation();

//This is ValueInformation()
private Argument[] ValueInformation()
{
    Argument[] args = new Argument[2];
    args[0] = new Argument();
    args[0].Name = "NetworkAdapter";
    args[0].Value = "55:88:99:11:22:33:44";
    args[0].Description = "This is iut CNC Program Context.";
    args[0].DataType = DataTypeIds.String;
    args[0].ValueRank = ValueRanks.Scalar;

    args[1] = new Argument();
    args[1].Name = "IP";
    args[1].Value = "127.0.0.1";
    args[1].Description = "This is Set IP";
    args[1].DataType = DataTypeIds.String;
    args[1].ValueRank = ValueRanks.Scalar;
}

I has set the two Arguments default value. But when i use opc ua client to call this server methods, the two Argument default value is show ""(no default value)? Why?

This is the result

Does the opc ua methods can't set default value with InputArguments?

If is ture, How can i use another way to achieve this function?