bool                                                                                 
  mongoc_bulk_operation_insert_with_opts (mongoc_bulk_operation_t *bulk,               
                                          const bson_t *document,                      
                                          const bson_t *opts,                          
                                          bson_error_t *error)                         
  {                                                                                    
....
     if (opts && bson_iter_init_find_case (&iter, opts, "legacyIndex") &&              
         bson_iter_as_bool (&iter)) {                                                  
        if (!_mongoc_validate_legacy_index (document, error)) {                        
           return false;                                                               
        }                                                                              
     } else if (!_mongoc_validate_new_document (document, error)) {                    
        return false;                                                                  
     }