Return a fully-qualified reference_image string.

def reference_image_path(cls, project, location, product, reference_image):
        """Return a fully-qualified reference_image string."""
        return google.api_core.path_template.expand(
            "projects/{project}/locations/{location}/products/{product}/referenceImages/{reference_image}",
            project=project,
            location=location,
            product=product,
            reference_image=reference_image,
        )