added missing files

lib/apis/core/heartbit/heartbeat.dart

@@ -0,0 +1,31 @@
+import 'dart:async';
+
+import 'package:event/event.dart';
+import 'package:walletconnect_flutter_v2/apis/core/heartbit/i_heartbeat.dart';
+
+class HeartBeat implements IHeartBeat {
+  Timer? _heartbeatTimer;
+
+  @override
+  int interval;
+
+  HeartBeat({this.interval = 5});
+
+  @override
+  void init() {
+    if (_heartbeatTimer != null) return;
+    _heartbeatTimer = Timer.periodic(
+      Duration(seconds: interval),
+      (timer) => onPulse.broadcast(),
+    );
+  }
+
+  @override
+  void stop() {
+    _heartbeatTimer?.cancel();
+    _heartbeatTimer = null;
+  }
+
+  @override
+  final Event<EventArgs> onPulse = Event();
+}

lib/apis/core/heartbit/i_heartbeat.dart

@@ -0,0 +1,9 @@
+import 'package:event/event.dart';
+
+abstract class IHeartBeat {
+  abstract int interval;
+  abstract final Event onPulse;
+
+  void init();
+  void stop();
+}