Expanded class hierarchy of TestHtmlSource

class \Drupal\tmgmt\SourcePluginBase extends \Drupal\Core\Plugin\PluginBase implements SourcePluginInterface
- class \Drupal\tmgmt_config\Plugin\tmgmt\Source\ConfigSource implements \Drupal\Core\Plugin\ContainerFactoryPluginInterface
- class \Drupal\tmgmt_content\Plugin\tmgmt\Source\ContentEntitySource implements ContinuousSourceInterface, SourcePreviewInterface
- class \Drupal\tmgmt_locale\Plugin\tmgmt\Source\LocaleSource
- class \Drupal\tmgmt_test\Plugin\tmgmt\Source\TestSource
  - class \Drupal\tmgmt_test\Plugin\tmgmt\Source\TestHtmlSource