Invalid types "text" and "date" specified in SolrFieldDefinition data defintions

Looks mostly good. A few notes, all addressed in the attached patch revision.

1. +++ b/src/EventSubscriber/SearchApiSubscriber.php
   @@ -20,24 +21,29 @@ class SearchApiSubscriber implements EventSubscriberInterface {
   +    $mapping['solr_text_custom'] = $mapping['text'];
   

   Should solr_text_custom_omit_norms be included here, too?

2. +++ b/src/Plugin/search_api/backend/SearchApiSolrBackend.php
   @@ -776,6 +776,7 @@ class SearchApiSolrBackend extends BackendPluginBase implements SolrBackendInter
   +      'solr_text_custom',
   

   I assume this should have the solr_text_custom_omit_norms type, too?

3. +++ b/src/Plugin/search_api/data_type/CustomTextDataType.php
   @@ -11,7 +11,7 @@ use Drupal\search_api\Plugin\search_api\data_type\TextDataType;
   - *   fallback_type = "text",
   + *   fallback_type = "search_api_text",
   

   For all of those: Fallback types should be Search API data types, so those are already correct as-is.

tested in some real environments

Automatically closed - issue fixed for 2 weeks with no activity.