Add shadow to border of modal bottom sheet

How can I add a shadow to the border of modal bottom sheet? Here's my code:

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
          useMaterial3: true,
          bottomSheetTheme: const BottomSheetThemeData(
              modalElevation: 1000.0,
              elevation: 1000.0,
              clipBehavior: Clip.hardEdge,
              shape: RoundedRectangleBorder(
                  borderRadius: BorderRadius.only(
                      topLeft: Radius.circular(20),
                      topRight: Radius.circular(20))))),
      home: TabBarDemo(),
    );
  }
}

class TabBarDemo extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
          body: ElevatedButton(
              child: Text('Press'),
              onPressed: () {
                showModalBottomSheet(
                    barrierColor: Colors.transparent,
                    context: context,
                    builder: (context) {
                      return Container();
                    });
              })),
    );
  }
}

Even though I've set the elevation property, I don't see any shadow on the border of the bottom sheet. Instead I see a plain border:

You can use boxShadow for this. Try this code.

Scaffold(
      body: Center(
        child: ElevatedButton(
          child: const Text('Press'),
          onPressed: () {
            showModalBottomSheet(
              barrierColor: Colors.transparent,
              context: context,
              builder: (context) {
                return Container(
                  height: 300,
                  decoration: BoxDecoration(
                    color: Colors.white,
                    borderRadius: BorderRadius.vertical(top: Radius.circular(30)),
                    boxShadow: [BoxShadow(color: Colors.grey, blurRadius: 10.0)],
                  ),
                );
              },
            );
          },
        ),
      ),
    );

The shadow is controlled by setting either the BottomSheetThemeData.modalElevation property or the elevation parameter in the call to showModalBottomSheet. BottomSheetThemeData.elevation appears to do nothing in my example. The shadow is not prominent and not controllable as with BoxShadow, but at least clipping works properly. In my question, the shadow was visible, but it was spread out because of the large modalElevation value.