add upgrade handler

Author: faddat

app/app.go

@@ -839,7 +839,13 @@ func (app *App) RegisterTendermintService(clientCtx client.Context) {
 
 // RegisterUpgradeHandlers returns upgrade handlers
 
-func (app *App) RegisterUpgradeHandlers(cfg module.Configurator) {}
+func (app *App) RegisterUpgradeHandlers(cfg module.Configurator) {
+	app.UpgradeKeeper.SetUpgradeHandler("MigrateTraces",
+		func(ctx sdk.Context, _ upgradetypes.Plan, fromVM module.VersionMap) (module.VersionMap, error) {
+			// transfer module consensus version has been bumped to 2
+			return app.mm.RunMigrations(ctx, cfg, fromVM)
+		})
+}
 
 // GetMaccPerms returns a copy of the module account permissions
 func GetMaccPerms() map[string][]string {