flutter: Make round corners in I am using NestedScrollView

Question

I am using NestedScrollView like this:

return Scaffold(
    backgroundColor: Colors.white,
    body: NestedScrollView(
      physics: const ClampingScrollPhysics(),
      floatHeaderSlivers: true,
      headerSliverBuilder: (BuildContext context, bool innerBoxIsScrolled) {
        return <Widget>[
          SliverAppBar(
            expandedHeight: MediaQuery.of(context).size.height - 200,
            floating: true,
            snap: true,
            forceElevated: innerBoxIsScrolled,
            flexibleSpace: FlexibleSpaceBar(
              background: GoogleMap(
                mapType: MapType.terrain,
                zoomGesturesEnabled: false,
                zoomControlsEnabled: false,
                initialCameraPosition: const CameraPosition(
                  target: LatLng(40.166672, 44.295783),
                  zoom: 14.4746,
                ),
                onMapCreated: (GoogleMapController controller) {
                },
                markers: {
                  Marker(
                    markerId: MarkerId(""),
                    position: LatLng(40.166672, 44.295783),
                  ),
                },
              ),
            ),
          ),
        ];
      },
      body: ClipRRect(
        borderRadius: BorderRadius.only(
          topLeft: Radius.circular(24),
          topRight: Radius.circular(24),
        ),
        child: CustomScrollView(...

I want to CustomScrollView top left and right corners rounded so I added ClipRRect or a container with rounded corners but did not work.