sendRaw method Null safety

Implementation

@override
Future<WebDriverResponse> sendRaw(WebDriverRequest request) async {
  await _lock.acquire();
  late HttpClientRequest httpRequest;

  switch (request.method) {
    case HttpMethod.httpGet:
      httpRequest = await client.getUrl(resolve(request.uri!));
      break;
    case HttpMethod.httpPost:
      httpRequest = await client.postUrl(resolve(request.uri!));
      break;
    case HttpMethod.httpDelete:
      httpRequest = await client.deleteUrl(resolve(request.uri!));
      break;
  }

  httpRequest.followRedirects = true;
  _headers.forEach(httpRequest.headers.add);
  httpRequest.headers.add(HttpHeaders.acceptHeader, 'application/json');
  httpRequest.headers.add(HttpHeaders.acceptCharsetHeader, utf8.name);
  httpRequest.headers.add(HttpHeaders.cacheControlHeader, 'no-cache');

  if (request.body != null && request.body!.isNotEmpty) {
    httpRequest.headers.contentType =
        ContentType('application', 'json', charset: 'utf-8');
    final body = utf8.encode(request.body!);
    httpRequest.contentLength = body.length;
    httpRequest.add(body);
  }

  try {
    final response = await httpRequest.close();

    return WebDriverResponse(response.statusCode, response.reasonPhrase,
        await utf8.decodeStream(response.cast<List<int>>()));
  } finally {
    _lock.release();
  }
}