Issue #3352946: Get forms are always validated

src/HookHandler/FormAlter.php

+<?php
+
+declare(strict_types = 1);
+
+namespace Drupal\ui_suite_bootstrap\HookHandler;
+
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\Render\Element;
+
+/**
+ * Alter forms.
+ */
+class FormAlter {
+
+  /**
+   * Alter forms.
+   *
+   * @param array $form
+   *   The form structure.
+   * @param \Drupal\Core\Form\FormStateInterface $formState
+   *   The form state.
+   * @param string $form_id
+   *   The form ID.
+   */
+  public function alter(array &$form, FormStateInterface $formState, string $form_id): void {
+    // See \Drupal\Core\Form\FormBuilder::processForm().
+    if ($formState->isMethodType('get') && $formState->getAlwaysProcess()) {
+      $form['#after_build'][] = [
+        static::class,
+        'afterBuildAddGetFormMethod',
+      ];
+    }
+  }
+
+  /**
+   * Form element #after_build callback.
+   */
+  public static function afterBuildAddGetFormMethod(array $element, FormStateInterface $form_state): array {
+    static::addGetFormMethod($element);
+    return $element;
+  }
+
+  /**
+   * Set form method to all form elements.
+   *
+   * To allow other processing to act based on this information.
+   *
+   * @param array $form
+   *   The form or form element which children should have form method attached.
+   */
+  protected static function addGetFormMethod(array &$form): void {
+    foreach (Element::children($form) as $child) {
+      if (!isset($form[$child]['#form_method'])) {
+        $form[$child]['#form_method'] = 'get';
+      }
+      static::addGetFormMethod($form[$child]);
+    }
+  }
+
+}