Optional end date as radios for future optional start date.

core/modules/datetime_range/config/schema/datetime_range.schema.yml

@@ -7,12 +7,12 @@ field.storage_settings.daterange:
   label: 'Date range settings'
 
 field.field_settings.daterange:
-  type: field.field_settings.datetime
+  type: mapping
   label: 'Date range settings'
   mapping:
-    optional_end_date:
-      type: boolean
-      label: 'Optional end date'
+    optional_values:
+      type: integer
+      label: 'Optional values'
 
 field.value.daterange:
   type: mapping