Migration guide for version 2.0.0

Documentation/version-update.md

@@ -8,6 +8,58 @@ parentDocSlug: flutter-sdk-release-notes
 
 This guide will help you upgrade your Exponea SDK to the new version.
 
+## Update from version 1.x.x to 2.x.x
+
+Updating the Exponea Flutter SDK to version 2.X.X from 1.X.X requires making some changes related to in-app messages Action Stream implementations.
+
+The inAppMessageActionStream was changed and simplified, so you have to migrate your implementation of in-app message action and close handling. This migration requires changing decision logic based on parameters coming from the stream.
+
+Your implementation may have been similar to the following example:
+
+```dart
+const overrideDefaultBehavior = false;
+const trackActions = false;
+final subscription = _plugin.inAppMessageActionStream(overrideDefaultBehavior: overrideDefaultBehavior, trackActions: trackActions).listen((inAppMessageAction) {
+  if (inAppMessageAction.button != null) {  
+      _plugin.trackInAppMessageClick(inAppMessageAction.message, inAppMessageAction.button);
+  } else {
+      _plugin.trackInAppMessageClose(inAppMessageAction.message, interaction: inAppMessageAction.interaction);
+  }
+});
+```
+
+To update to version 2 of the SDK, you must recognize the inAppMessageAction event by its `type` parameter and refactor your code as follows:
+
+```dart
+const overrideDefaultBehavior = false;
+const trackActions = false;
+final subscription = _plugin.inAppMessageActionStream(overrideDefaultBehavior: overrideDefaultBehavior, trackActions: trackActions).listen((inAppMessageAction) {
+  if (<your-special-condition>) {
+    switch(inAppMessageAction.type) {
+      case InAppMessageActionType.click:
+        _plugin.trackInAppMessageClick(inAppMessageAction.message!, inAppMessageAction.button!);
+        break;
+      case InAppMessageActionType.close:
+        _plugin.trackInAppMessageClose(inAppMessageAction.message!, button: inAppMessageAction.button, interaction: inAppMessageAction.interaction ?? true);
+        break;
+      case InAppMessageActionType.error:
+        // Here goes your code
+        break;
+      case InAppMessageActionType.show:
+        // Here goes your code
+        break;
+    }
+  }
+});
+```
+
+A benefit of the new behavior is that the method inAppMessageCloseAction can be called with a non-null button parameter. This happens when a user clicks on the Cancel button and enables you to determine which button has been clicked by reading the button text.
+
+### inAppMessageAction scheme change
+
+inAppMessageActionStream also emits Show and Error events. You can distinguish events by introduced `type` parameter in `inAppMessageAction`.
+As not all values are reported for each type, `interaction` and `InAppMessage` in scheme become nullable.
+
 ## Update from version 0.x.x to 1.x.x
 
 Updating the Exponea Flutter SDK to version 1 and higher requires making some changes related to Firebase push notifications.