如何在flutter中为google地图添加边界半径？

dependencies:
  flutter:
    sdk: flutter
  google_maps_flutter: ^2.0.10

import 'package:google_maps_flutter/google_maps_flutter.dart';

GoogleMapController? _mapController;

GoogleMap(
  onMapCreated: (GoogleMapController controller) {
    _mapController = controller;
  },
  // 其他地图参数设置
)

Polygon(
  polygonId: PolygonId('boundary'),
  points: [
    // 边界点的经纬度
    LatLng(37.77483, -122.41942),
    LatLng(37.77483, -122.43142),
    LatLng(37.76683, -122.43142),
    LatLng(37.76683, -122.41942),
  ],
  strokeWidth: 2,
  strokeColor: Colors.red,
  fillColor: Colors.red.withOpacity(0.5),
)

GoogleMap(
  onMapCreated: (GoogleMapController controller) {
    _mapController = controller;
  },
  polygons: {
    // 添加Polygon小部件
    Polygon(
      polygonId: PolygonId('boundary'),
      points: [
        // 边界点的经纬度
        LatLng(37.77483, -122.41942),
        LatLng(37.77483, -122.43142),
        LatLng(37.76683, -122.43142),
        LatLng(37.76683, -122.41942),
      ],
      strokeWidth: 2,
      strokeColor: Colors.red,
      fillColor: Colors.red.withOpacity(0.5),
    ),
  },
  // 其他地图参数设置
)