Resolve #3500045 "Text filter is"

Closes #3500045

config/schema/views_csv_source.views.schema.yml

@@ -18,6 +18,19 @@ views.filter.views_csv_source_filter:
     key:
       type: string
       label: 'Column name key'
+    expose:
+      type: mapping
+      label: 'Exposed'
+      mapping:
+        required:
+          type: boolean
+          label: 'Required'
+        placeholder:
+          type: label
+          label: 'Placeholder'
+    value:
+      type: string
+      label: 'Value'
 
 views.filter.views_csv_source_filter_select:
   type: views_filter