Synchronize access to CT Wrapper (#517)

Author: hborisoff

AndroidSDKCore/src/main/java/com/leanplum/internal/RequestSender.java

@@ -143,16 +143,16 @@ public void sendRequests() {
         int statusCode = op.getResponseCode();
 
         if (statusCode >= 200 && statusCode <= 299) {
-          if (MigrationManager.refreshStateMidSession(responseBody)) { // TODO if current multi response contains getMigrateState this line would cause a second call, because getMigrateState response wouldn't be parsed yet
-            Log.i("Migration state will be refreshed.");
-          }
-
           if (RequestUtil.updateApiConfig(responseBody)) {
             // API config is changed and we need to send requests again
             sendRequests();
             return;
           }
 
+          if (MigrationManager.refreshStateMidSession(responseBody)) {
+            Log.i("Migration state will be refreshed.");
+          }
+
           // Parse response body and trigger callbacks
           invokeCallbacks(responseBody);
 

AndroidSDKCore/src/main/java/com/leanplum/migration/MigrationManager.kt

@@ -17,6 +17,7 @@ object MigrationManager {
 
   @JvmStatic
   var wrapper: IWrapper = NullWrapper
+    @Synchronized get
     private set
 
   @JvmStatic
@@ -27,6 +28,7 @@ object MigrationManager {
     }
 
   @JvmStatic
+  @Synchronized
   fun updateWrapper() {
     if (Constants.isNoop()) {
       wrapper = NullWrapper
@@ -87,8 +89,6 @@ object MigrationManager {
       fetchStateAsync { success ->
         if (success) {
           // transition side effects are handled in fetchStateAsync
-        } else {
-          // TODO guard against continuous failure?
         }
       }
       return true