Resource server is returning `Internal Server Error` when using Opaque Token with the new Spring Authorization Server

I created a spring authorization server, setting it to produce opaque tokens.

I also created a spring resource server, setting it to accept opaque tokens and verify the tokens via introspection URI /oauth2/introspect (which is btw in spring authorization server)

There is no problem in generating the opaque token by the spring authorization server.

But once I tried to GET request from resource server, I receive "Internal Server Error".

{
    "timestamp": "2022-09-20T06:59:40.194+00:00",
    "status": 500,
    "error": "Internal Server Error",
    "path": "/articles"
}

By the way, if I use JWT token, there is no problem. But unfortunately, I will have to use opaque tokens.

Hope somebody can share some ideas.

Thanks.