reflect backend updates in state for databricks_app

internal/providers/pluginfw/products/app/resource_app.go

@@ -177,15 +177,15 @@ func (a *resourceApp) Update(ctx context.Context, req resource.UpdateRequest, re
 	if resp.Diagnostics.HasError() {
 		return
 	}
-	_, err := w.Apps.Update(ctx, apps.UpdateAppRequest{App: &appGoSdk, Name: app.Name.ValueString()})
+	response, err := w.Apps.Update(ctx, apps.UpdateAppRequest{App: &appGoSdk, Name: app.Name.ValueString()})
 	if err != nil {
 		resp.Diagnostics.AddError("failed to update app", err.Error())
 		return
 	}
 
 	// Store the updated version of the app in state
 	var newApp apps_tf.App
-	resp.Diagnostics.Append(converters.GoSdkToTfSdkStruct(ctx, appGoSdk, &newApp)...)
+	resp.Diagnostics.Append(converters.GoSdkToTfSdkStruct(ctx, response, &newApp)...)
 	if resp.Diagnostics.HasError() {
 		return
 	}

internal/providers/pluginfw/products/app/resource_app_acc_test.go

@@ -6,6 +6,8 @@ import (
 	"testing"
 
 	"github.com/databricks/terraform-provider-databricks/internal/acceptance"
+	"github.com/hashicorp/terraform-plugin-testing/terraform"
+	"github.com/stretchr/testify/assert"
 )
 
 const baseResources = `
@@ -118,14 +120,24 @@ is required`)),
 }
 
 func TestAccAppResource(t *testing.T) {
+	var updateTime string
 	acceptance.LoadWorkspaceEnv(t)
 	if acceptance.IsGcp(t) {
 		acceptance.Skipf(t)("not available on GCP")
 	}
 	acceptance.WorkspaceLevel(t, acceptance.Step{
 		Template: makeTemplate("My app"),
+		Check: func(s *terraform.State) error {
+			updateTime = s.RootModule().Resources["databricks_app.this"].Primary.Attributes["update_time"]
+			return nil
+		},
 	}, acceptance.Step{
 		Template: makeTemplate("My new app"),
+		Check: func(s *terraform.State) error {
+			var newUpdateTime = s.RootModule().Resources["databricks_app.this"].Primary.Attributes["update_time"]
+			assert.NotEqual(t, updateTime, newUpdateTime)
+			return nil
+		},
 	}, acceptance.Step{
 		ImportState:       true,
 		ResourceName:      "databricks_app.this",