diff --git a/pkg/filter/ws/config.go b/pkg/filter/ws/config.go
index 3982d658..04ba8cb1 100644
--- a/pkg/filter/ws/config.go
+++ b/pkg/filter/ws/config.go
@@ -128,6 +128,9 @@ const filterSchema = `
                 "clientSecret": {
                     "type": "string"
                 },
+                "grantType": {
+                    "type": "string"
+                },
                 "tokenUrl": {
                     "type": "string"
                 },