2.x Convert generators to plugins

By: alex.skrypnyk

Summary

This pull request converts the generated content system from a hook-based architecture to a Drupal plugin-based system (#3556829). Generators are now discovered as PHP classes with a #[GeneratedContent] attribute in src/Plugin/GeneratedContent/ directories.

Key Changes

Core Infrastructure

• New plugin system: Introduces GeneratedContent attribute class for marking generator plugins and GeneratedContentPluginManager for discovering and managing plugins.
• Plugin interface and base class: Adds GeneratedContentPluginInterface and GeneratedContentPluginBase to standardize plugin implementations with methods for generate(), getEntityType(), getBundle(), getWeight(), and getTracking().
• Service registration: Registers plugin.manager.generated_content service in generated_content.services.yml.
• Repository refactoring: Updates GeneratedContentRepository to use the plugin manager instead of scanning module hooks and loading .inc files. Removes ModuleHandlerInterface and EntityTypeBundleInfoInterface dependencies.
• Form updates: Updates GeneratedContentForm to guide users toward the plugin-based approach.

Example Module Migrations

All hook-based generators in example modules (generated_content_example1 and generated_content_example2) are converted to plugin classes:

Example 1:

• Removed hook implementations: generated_content_create_file_file, generated_content_create_media_image, generated_content_create_taxonomy_term_tags, generated_content_create_user_user
• Added plugins: File, MediaImage, TaxonomyTermTags, User

Example 2:

• Removed hook implementations: generated_content_create_node_article, generated_content_create_node_page (with variations), generated_content_create_media_document, generated_content_create_taxonomy_term_tags
• Added plugins: NodeArticle, NodePage (with variation support), MediaDocument, TaxonomyTermTags

Removed Files

All procedural hook files have been deleted:

• generated_content.api.php (main hook documentation)
• Multiple .inc files from example modules defining weight, tracking, and creation hooks

Runtime Plugin Alteration

Support for hook_generated_content_plugin_alter() is now documented, enabling runtime modification of plugin definitions.

Migration Impact

This change represents a significant architectural shift from hook-based to plugin-based content generation, aligning with modern Drupal practices. All existing generators must be refactored as plugin classes to continue functioning.