appservice slot resources - fix error when removing auth_settings_v2 blocks (#32008)

[BUG] * `azurerm_linux_web_app_slot`, `azurerm_windows_web_app_slot`, `azurerm_windows_function_app_slot`, `azurerm_linux_function_app_slot` - fix API error when removing auth_settings_v2 configuration from a previously deployed appservice slot [GH-32008]

Author: toddgiguere

internal/services/appservice/linux_function_app_slot_resource.go

@@ -1077,6 +1077,10 @@ func (r LinuxFunctionAppSlotResource) Update() sdk.ResourceFunc {
 
 			if metadata.ResourceData.HasChange("auth_settings_v2") {
 				authV2Update := helpers.ExpandAuthV2Settings(state.AuthV2Settings)
+				// (@toddgiguere) - in the case of a removal of this block, we need to zero these settings
+				if authV2Update.Properties == nil {
+					authV2Update.Properties = helpers.DefaultAuthV2SettingsProperties()
+				}
 				if _, err := client.UpdateAuthSettingsV2Slot(ctx, *id, *authV2Update); err != nil {
 					return fmt.Errorf("updating AuthV2 Settings for Linux %s: %+v", id, err)
 				}

internal/services/appservice/linux_web_app_slot_resource.go

@@ -891,6 +891,10 @@ func (r LinuxWebAppSlotResource) Update() sdk.ResourceFunc {
 
 			if metadata.ResourceData.HasChange("auth_settings_v2") {
 				authV2Update := helpers.ExpandAuthV2Settings(state.AuthV2Settings)
+				// (@toddgiguere) - in the case of a removal of this block, we need to zero these settings
+				if authV2Update.Properties == nil {
+					authV2Update.Properties = helpers.DefaultAuthV2SettingsProperties()
+				}
 				if _, err := client.UpdateAuthSettingsV2Slot(ctx, *id, *authV2Update); err != nil {
 					return fmt.Errorf("updating AuthV2 Settings for Linux %s: %+v", id, err)
 				}

internal/services/appservice/windows_function_app_slot_resource.go

@@ -1093,6 +1093,10 @@ func (r WindowsFunctionAppSlotResource) Update() sdk.ResourceFunc {
 
 			if metadata.ResourceData.HasChange("auth_settings_v2") {
 				authV2Update := helpers.ExpandAuthV2Settings(state.AuthV2Settings)
+				// (@toddgiguere) - in the case of a removal of this block, we need to zero these settings
+				if authV2Update.Properties == nil {
+					authV2Update.Properties = helpers.DefaultAuthV2SettingsProperties()
+				}
 				if _, err := client.UpdateAuthSettingsV2Slot(ctx, *id, *authV2Update); err != nil {
 					return fmt.Errorf("updating AuthV2 Settings for Windows %s: %+v", id, err)
 				}

internal/services/appservice/windows_web_app_slot_resource.go

@@ -974,6 +974,10 @@ func (r WindowsWebAppSlotResource) Update() sdk.ResourceFunc {
 
 			if metadata.ResourceData.HasChange("auth_settings_v2") {
 				authV2Update := helpers.ExpandAuthV2Settings(state.AuthV2Settings)
+				// (@toddgiguere) - in the case of a removal of this block, we need to zero these settings
+				if authV2Update.Properties == nil {
+					authV2Update.Properties = helpers.DefaultAuthV2SettingsProperties()
+				}
 				if _, err := client.UpdateAuthSettingsV2Slot(ctx, *id, *authV2Update); err != nil {
 					return fmt.Errorf("updating AuthV2 Settings for Linux %s: %+v", *id, err)
 				}