Why WebSocketChannel not allowed unsecure urls ?

[rkhkr]

E/flutter (29567): [ERROR:flutter/lib/ui/ui_dart_state.cc(184)] Unhandled Exception: Bad state: Insecure HTTP is not allowed by platform: http://192.168.111.20:8098
E/flutter (29567): #0 _HttpClient._openUrl (dart:_http/http_impl.dart:2435:7)
E/flutter (29567): #1604 _HttpClient.openUrl (dart:_http/http_impl.dart:2342:7)
E/flutter (29567): dart-lang/web_socket_channel#2 _WebSocketImpl.connect (dart:_http/websocket_impl.dart:1025:24)
E/flutter (29567): dart-lang/web_socket_channel#3 WebSocket.connect (dart:_http/websocket.dart:379:22)
E/flutter (29567): #1605 new IOWebSocketChannel.connect (package:web_socket_channel/io.dart:57:55)
E/flutter (29567): dart-lang/web_socket_channel#5 connect (package:web_socket_channel/src/_connect_io.dart:12:57)
E/flutter (29567): dart-lang/web_socket_channel#6 new WebSocketChannel.connect (package:web_socket_channel/src/channel.dart:106:48)

From Android 9 Pie and above its showing insecure error.
I got solution by adding android:usesCleartextTraffic="true" in android/app/src/main/AndroidManifest.xml

[robertpiosik]

For those having this appearing in search results, read more about the issue here.