Issue #3412037 by erik_petra: Error: Class "ResponsiveImageFormatter" not found

src/Plugin/Transform/Field/ResponsiveImageTransform.php → modules/transform_api_responsive_image/src/Plugin/Transform/Field/ResponsiveImageTransform.php

 <?php
 
-namespace Drupal\transform_api\Plugin\Transform\Field;
+namespace Drupal\transform_api_responsive_image\Plugin\Transform\Field;
 
 use Drupal\Core\Cache\CacheableMetadata;
 use Drupal\Core\Field\FieldItemListInterface;
@@ -97,7 +97,7 @@ class ResponsiveImageTransform extends ResponsiveImageFormatter implements Field
     foreach ($sources as $source) {
       $parts = explode(" ", trim($source));
       $url = $this->pathToUrl($parts[0]);
-      $result[] = $url->toString() . ' ' . $parts[1];
+      $result[] = $url->toString() . ' ResponsiveImageTransform.php' . $parts[1];
     }
     return implode(', ', $result);
   }

modules/transform_api_responsive_image/transform_api_responsive_image.info.yml

+name: Transform API Responsive Image
+description: Adds responsive image features to Transform API.
+type: module
+package: Web services
+core_version_requirement: ^9 || ^10
+
+dependencies:
+  - core:responsive_image
+  - transform_api:transform_api

transform_api.install

@@ -24,3 +24,12 @@ function transform_api_update_9002() {
   \Drupal::entityDefinitionUpdateManager()
     ->installEntityType(\Drupal::entityTypeManager()->getDefinition('transform_block'));
 }
+
+/**
+ * Install transform_api_responsive_image.
+ */
+function transform_api_update_9003() {
+  /** @var \Drupal\Core\Extension\ModuleInstaller $installer */
+  $installer = \Drupal::service('module_installer');
+  $installer->install(['transform_api_responsive_image']);
+}