Handling of nillable = true & null primitive types

[jamienich]

The generated types don't include null when the wsdl element attribute nillable=true is set.
i.e.
my_generated_field string|null,

When the wsdl is parsed, nillable field settings can likely be inspected, to set null primitive types.
I may try and change the library to allow for literals which include the type and null (i.e. string|null) in the below code somewhere

function parseWsdl....
                                if (outputMessage.element) {
                                    const typeName = outputMessage.element.$type ?? outputMessage.element.$name;
                                    const type = parsedWsdl.findDefinition(typeName);
                                    outputDefinition = type ?? parseDefinition(
                                        parsedWsdl,
                                        mergedOptions,
                                        typeName,
                                        outputMessage.parts,
                                        [typeName],
                                        visitedDefinitions
                                    );
                                    // Check for nillable attribute
                                    **if (outputMessage.element.$nillable === "true") {
                                        //change the type definition from string to string|null**

Does this sound reasonable?