Issue #3296577 Apply patch, modify some of the weird things it did

Closes #3296577

modules/api_proxy_example/src/Plugin/api_proxy/Example.php

@@ -29,7 +29,7 @@ final class Example extends HttpApiPluginBase {
     $form['more_stuff'] = [
       '#type' => 'textfield',
       '#title' => $this->t('Extra config'),
-      '#default_value' => $this->configuration['more_stuff'],
+      '#default_value' => $this->configuration['more_stuff'] ?? [],
     ];
     return $form;
   }