我在SpringCloudGateway中有这样的配置：

security:
    oauth2:
      client:
        registration:
          gateway:
            provider: uaa
            client-id: gateway
            client-secret: secret
            authorization-grant-type: authorization_code
            redirect-uri-template: "{baseUrl}/login/oauth2/code/{registrationId}"
            scope: openid,profile,email,resource.read
        provider:
          uaa:
            authorization-uri: http://localhost:8090/uaa/oauth/authorize
            token-uri: http://uaa:8090/uaa/oauth/token
            user-info-uri: http://uaa:8090/uaa/userinfo
            user-name-attribute: sub
            jwk-set-uri: http://uaa:8090/uaa/token_keys

但是我想在auth请求中指定额外的参数，例如：loginpage=test.jsp如何做到这一点？