Reusing methods in go which operate on struct values

I am trying to share a single method across multiple structs in go. I do not want to have to redefine the method across every struct.

I realise that code reusability in go is achieved by using composition over inheritance. However I have no idea how to use the concept in my current use case. My code is the following:

package mypackage

import (
	"net/url"
	"reflect"
)


// Build a query string from a query struct
func (params ListShipmentsQuery) toQueryString() string {
	query := url.Values{}
	values := reflect.ValueOf(params)
	types := values.Type()
	for i := 0; i < values.NumField(); i++ {
		value := values.Field(i).Interface().(string)
		if value != "" {
			query.Add(types.Field(i).Tag.Get("url"), value)
		}

	}

	return query.Encode()
}

type ListShipmentsQuery struct {
	ShipmentId string `url:"shipment_id"`
	OrderId string `url:"order_id"`
}

type ListProductsQuery struct {
	Sku string `url:"sku"`
	Name string `url:"name"`
}

How can I apply the same method to the ListProductsQuery struct without repeating myself? The method must use the properties that make up the struct.

For example in PHP using inheritance I would do:

class Parent 
{
    public function toQueryString()
    {
        // Logic to grab properties and build query string
    }
}

class Child {}

$c = new Child();
$query_string = $c.toQueryString();

I have tried implementing another struct via composition but I have no way of passing the "parent's" properties to the struct which will have the shared method.

here's an example using generics, I would still probably go for the simple function example suggested in the comments, but this is surely useful for certain cases:

package main

import (
	"fmt"
	"net/url"
	"reflect"
)

func main() {
	{

		p := Parent[ListShipmentsQuery]{}
		p.child.ShipmentId = "hi"
		p.child.OrderId = "hi"
		fmt.Println(p.toQueryString())
	}
	{

		p := Parent[ListProductsQuery]{}
		p.child.Sku = "hi"
		p.child.Name = "hi"
		fmt.Println(p.toQueryString())
	}
}

type Parent[C any] struct {
	child C
}

func (p *Parent[C]) toQueryString() string {
	query := url.Values{}
	values := reflect.ValueOf(p.child)
	types := values.Type()
	for i := 0; i < values.NumField(); i++ {
		value := values.Field(i).Interface().(string)
		if value != "" {
			query.Add(types.Field(i).Tag.Get("url"), value)
		}

	}
	return query.Encode()
}

type ListShipmentsQuery struct {
	ShipmentId string `url:"shipment_id"`
	OrderId    string `url:"order_id"`
}

type ListProductsQuery struct {
	Sku  string `url:"sku"`
	Name string `url:"name"`
}