Expanded class hierarchy of Spellcheck in Search API Solr 4.x
- class \Drupal\search_api_solr\Plugin\search_api_autocomplete\suggester\Spellcheck extends \Drupal\search_api_autocomplete\Suggester\SuggesterPluginBase implements PluginFormInterface uses \Drupal\search_api\Plugin\PluginFormTrait, BackendTrait