handleDownEvent(evt) {
    if (!this.condition_(evt)) {
      return false;
    }
    const pixelCoordinate = evt.coordinate;
    const insertVertices =
      this.findInsertVerticesAndUpdateDragSegments_(pixelCoordinate);

    if (insertVertices?.length && this.insertVertexCondition_(evt)) {
      this.willModifyFeatures_(evt, insertVertices);

      if (this.vertexFeature_) {
        const vertex = this.vertexFeature_.getGeometry().getCoordinates();
        for (let j = insertVertices.length - 1; j >= 0; --j) {
          this.insertVertex_(insertVertices[j], vertex);
        }
        this.ignoreNextSingleClick_ = true;
      }
    }

    return !!this.vertexFeature_;
  }
Handle pointer down events.
@param {import("../MapBrowserEvent.js").default} evt Event.
@return {boolean} If the event was consumed.
@override