Issue #3510596 by goz, just_like_good_vibes: [2.0.4] Improve prop value rendering for booleans

Closes #3510596

src/Element/ComponentElementBuilder.php

@@ -98,19 +98,39 @@ class ComponentElementBuilder implements TrustedCallbackInterface {
       }
     }
     else {
-      if (!empty($data) || $prop_type->getPluginId() === 'attributes') {
-        // For JSON Schema validator, empty value is not the same as missing
-        // value, and we want to prevent some of the prop types rules to be
-        // applied on empty values: string pattern, string format,
-        // enum, number min/max...
-        // However, we don't remove empty attributes to avoid an error with
-        // Drupal\Core\Template\TwigExtension::createAttribute() when themers
-        // forget to use the default({}) filter.
+      if (!static::isPropValueEmpty($data, $prop_type)) {
         $build['#props'][$prop_or_slot_id] = $data;
       }
     }
   }
 
+  /**
+   * Determine if a prop value is empty.
+   *
+   * @param mixed $data
+   *   The prop value.
+   * @param \Drupal\ui_patterns\PropTypeInterface $prop_type
+   *   Target prop type.
+   *
+   * @return bool
+   *   TRUE if the prop value is empty, FALSE otherwise.
+   */
+  protected static function isPropValueEmpty(mixed $data, PropTypeInterface $prop_type): bool {
+    // For JSON Schema validator, empty value is not the same as missing
+    // value, and we want to prevent some of the prop types rules to be
+    // applied on empty values: string pattern, string format,
+    // enum, number min/max...
+    // However, we don't remove empty attributes to avoid an error with
+    // Drupal\Core\Template\TwigExtension::createAttribute() when themers
+    // forget to use the default({}) filter.
+    // For boolean values, we only remove NULL values.
+    return match ($prop_type->getPluginId()) {
+      'attributes' => FALSE,
+      'boolean' => ($data === NULL),
+      default => empty($data),
+    };
+  }
+
   /**
    * Update the build array for a configured source on a prop/slot.
    *