context_header.go
func (c headerCtx) Child() ContextWithHeaders {
	var headersCopy headersContainer
	if h := c.headers(); h != nil {
		headersCopy = *h
	}

	return Wrap(context.WithValue(c.Context, contextKeyHeaders, &headersCopy))
}
func (c headerCtx) Child() ContextWithHeaders {
	var headersCopy headersContainer
	if h := c.headers(); h != nil {
		headersCopy = *h
	}

	return Wrap(context.WithValue(c.Context, contextKeyHeaders, &headersCopy))
}
// Child creates a child context with a separate container for headers.