Separate entity classes on different files

lib/entity_class/button_entity.class.dart

@@ -0,0 +1,25 @@
+part of '../main.dart';
+
+class ButtonEntity extends Entity {
+  ButtonEntity(Map rawData) : super(rawData);
+
+  @override
+  void sendNewState(newValue) {
+    eventBus.fire(new ServiceCallEvent(_domain, "turn_on", _entityId, null));
+  }
+
+  @override
+  Widget _buildActionWidget(bool inCard, BuildContext context) {
+    return FlatButton(
+      onPressed: (() {
+        sendNewState(null);
+      }),
+      child: Text(
+        "EXECUTE",
+        textAlign: TextAlign.right,
+        style:
+        new TextStyle(fontSize: Entity.STATE_FONT_SIZE, color: Colors.blue),
+      ),
+    );
+  }
+}