createOrUpdateVertexFeature_(coordinates, features, geometries, existing) {
    let vertexFeature = this.vertexFeature_;
    if (!vertexFeature) {
      vertexFeature = new Feature(new Point(coordinates));
      this.vertexFeature_ = vertexFeature;
      this.overlay_.getSource().addFeature(vertexFeature);
    } else {
      const geometry = vertexFeature.getGeometry();
      geometry.setCoordinates(coordinates);
    }
    vertexFeature.set('features', features);
    vertexFeature.set('geometries', geometries);
    vertexFeature.set('existing', existing);
    return vertexFeature;
  }
@param {import("../coordinate.js").Coordinate} coordinates Coordinates.
@param {Array<Feature>} features The features being modified.
@param {Array<import("../geom/SimpleGeometry.js").default>} geometries The geometries being modified.
@param {boolean} existing The vertex represents an existing vertex.
@return {Feature} Vertex feature.
@private