copy and modify the routes test for the legacy server

pkg/oidc/token_request.go

@@ -50,6 +50,16 @@ const (
 	JWTTokenType     TokenType = "urn:ietf:params:oauth:token-type:jwt"
 )
 
+func (t GrantType) IsSupported() bool {
+	for _, gt := range AllGrantTypes {
+		if t == gt {
+			return true
+		}
+	}
+
+	return false
+}
+
 var AllTokenTypes = []TokenType{
 	AccessTokenType, RefreshTokenType, IDTokenType, JWTTokenType,
 }