How does Spring Boot RSocket detect disconnection?

everyone.
I want to make chatting server using RSocket.
The code below stores user information when the user accesses it.

  private final List<RSocketRequester> CLIENTS = new ArrayList<>();

  @ConnectMapping
  public void onConnect(RSocketRequester reqer) {
    log.info("RSocket Connect Mapping Start : reqer {}", reqer.hashCode());

    reqer.rsocket()
        .onClose()
        .doFirst(() -> CLIENTS.add(reqer))
        .doOnError(error -> log.info("RSocket Connect Error : error {}", error))
        .doFinally(consumer -> {
          CLIENTS.remove(reqer);
        })
        .subscribe();

    log.info("RSocket Connect Mapping End : Clients {}", this.CLIENTS.size());
  }

spring:
  rsocket:
    server:
      port: 6565
      transport: websocket
      mapping-path: /rs

I want to get user information when the user disconnects.
Can the RSocket detect when the user disconnects?
help me please.

If you configured rsocket security you can access AuthenticationPrincipal at onConnect().

Simple example

@ConnectMapping
public void onConnect(RSocketRequester requester, @AuthenticationPrincipal Jwt principal) {
    requester.rsocket()
            .onClose()
            .doFirst(() -> {
                System.out.println(principal.getSubject());
                System.out.println("-----------------CONNNEEEECTED-----------------");
            })
            .doOnError(error -> {
            })
            .doFinally(consumer -> {
                System.out.println(principal.getSubject());
                System.out.println("-----------------DISCONNNNNECTED-----------------");
            })
            .subscribe();
}