Issue #2678564 by alexpott, Gábor Hojtsy: A missing schema to support migrate UI - source_base_path and database_state_key

core/modules/file/config/schema/file.destination.schema.yml

@@ -5,6 +5,9 @@ migrate.destination.entity:file:
     source_path_property:
       type: string
       label: 'Source path'
+    source_base_path:
+      type: string
+      label: 'Source base path'
     urlencode:
       type: boolean
       label: 'Whether to urlencode incoming file paths'

core/modules/migrate/config/schema/migrate.data_types.schema.yml

@@ -25,6 +25,9 @@ migrate_source:
     constants:
       type: ignore
       label: 'Constants'
+    database_state_key:
+      type: string
+      label: 'Key in state where the source database settings are stored'
 
 migrate_process:
   type: migrate_plugin