code: function serializeUserData(object) {
        try {
          return JSON.parse(JSON.stringify(object.userData));
        } catch (error) {
          console.warn(
            "THREE.GLTFExporter: userData of '" +
              object.name +
              "' " +
              "won't be serialized because of JSON.stringify error - " +
              error.message
          );
  
          return {};
        }
      }
docs: Serializes a userData.
  
  @param {THREE.Object3D|THREE.Material} object
  @returns {Object}