Update to Drupal 8.0.0-beta15. For more information, see: https://www.drupal.org/node/2563023

core/modules/user/config/schema/user.source.schema.yml

@@ -0,0 +1,47 @@
+# Schema for the user module's migration source plugins.
+
+migrate.source.d6_user:
+  type: migrate_source_sql
+  label: 'Drupal 6 user'
+  mapping:
+    constants:
+      type: mapping
+      label: 'Constants'
+      mapping:
+        key:
+          type: string
+          label: 'User data key'
+        module:
+          type: string
+          label: 'Module name'
+
+migrate.source.d6_user_picture_file:
+  type: migrate_source_sql
+  label: 'Drupal 6 user picure display'
+  mapping:
+    constants:
+      type: mapping
+      label: 'Constant'
+      mapping:
+        is_public:
+          type: boolean
+          label: 'Public'
+
+migrate.source.d6_user_picture_instance:
+  type: migrate_source_sql
+  label: 'Drupal 6 user picure display'
+  mapping:
+    provider:
+      type: string
+      label: 'Provider'
+    constants:
+      type: migrate_entity_constant
+      label: 'Constants'
+
+migrate.source.profile_field:
+  type: migrate_source_sql
+  label: 'Profile field'
+  mapping:
+    constants:
+      type: migrate_entity_constant
+      label: 'Constants'