refact lauchMiniProgram function in flutter

lib/src/models/wechat_launchminiprogram_model.dart

-/*
- * Copyright (C) 2018 The OpenFlutter Organization
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-import 'package:flutter/foundation.dart';
-import '../wechat_type.dart';
-class WeChatLaunchMiniProgramModel {
-  final String username;
-  final String path;
-  final WXMiniProgramType miniprogramtype;
-
-  WeChatLaunchMiniProgramModel({@required this.username, this.path, this.miniprogramtype})
-      : assert(username != null && username.trim().isNotEmpty);
-
-  Map toMap() {
-    return {"userName": username, "path": path, "miniProgramType": miniprogramtype};
-  }
-}
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