writeCircleGeometry_(feature, geometry) {
    const coordinates = geometry.getCenter();

    /** @type {SegmentData} */
    const centerSegmentData = {
      feature: feature,
      geometry: geometry,
      index: CIRCLE_CENTER_INDEX,
      segment: [coordinates, coordinates],
    };

    /** @type {SegmentData} */
    const circumferenceSegmentData = {
      feature: feature,
      geometry: geometry,
      index: CIRCLE_CIRCUMFERENCE_INDEX,
      segment: [coordinates, coordinates],
    };

    const featureSegments = [centerSegmentData, circumferenceSegmentData];
    centerSegmentData.featureSegments = featureSegments;
    circumferenceSegmentData.featureSegments = featureSegments;
    this.rBush_.insert(createExtent(coordinates), centerSegmentData);
    let circleGeometry = /** @type {import("../geom/Geometry.js").default} */ (
      geometry
    );
    const userProjection = getUserProjection();
    if (userProjection && this.getMap()) {
      const projection = this.getMap().getView().getProjection();
      circleGeometry = circleGeometry
        .clone()
        .transform(userProjection, projection);
      circleGeometry = fromCircle(
        /** @type {import("../geom/Circle.js").default} */ (circleGeometry),
      ).transform(projection, userProjection);
    }
    this.rBush_.insert(circleGeometry.getExtent(), circumferenceSegmentData);
  }
We convert a circle into two segments.  The segment at index
{@link CIRCLE_CENTER_INDEX} is the
circle's center (a point).  The segment at index
{@link CIRCLE_CIRCUMFERENCE_INDEX} is
the circumference, and is not a line segment.

@param {Feature} feature Feature.
@param {import("../geom/Circle.js").default} geometry Geometry.
@private