--- /dev/null
+<?php
+
+namespace Drupal\settings_tray_test\Plugin\Block;
+
+use Drupal\Core\Block\BlockBase;
+
+/**
+ * Block that does nothing explicit for Settings Tray.
+ *
+ * @Block(
+ * id = "settings_tray_test_none",
+ * admin_label = "Settings Tray test block: forms[settings_tray] is not specified",
+ * )
+ */
+class SettingsTrayFormAnnotationNoneBlock extends BlockBase {
+
+ /**
+ * {@inheritdoc}
+ */
+ public function build() {
+ return ['#markup' => '<span>none</span>'];
+ }
+
+}