gltf_importer.py (Source)

class glTF2ImportUserExtension:
    def __init__(self):
        from io_scene_gltf2.io.com.gltf2_io_extensions import Extension
        self.properties = bpy.context.scene.OmmImporterExtensionProperties
        self.extensions = [Extension(name="NONE_opacity_micromap",
                                     extension={},
                                     required=False)]
    def gather_import_mesh_after_hook(self, gltf2_mesh, blender_mesh, gltf):
        if self.properties.enabled:
            create_micromap_attributes(gltf2_mesh, blender_mesh)