Issue #3519282 by pdureau: Add PluginSettingsInterface::settingsSummary()

Closes #3519282

src/Plugin/UiPatterns/Source/EntityFieldSource.php

@@ -35,6 +35,16 @@ class EntityFieldSource extends DerivableContextSourceBase {
     return $form;
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function settingsSummary(): array {
+    $derivable_context = explode(':', $this->getSetting("derivable_context") ?? '');
+    return [
+      $derivable_context[array_key_last($derivable_context)],
+    ];
+  }
+
   /**
    * {@inheritDoc}
    */