Convey to CAS that this is your CAS client/service by setting up this bean. Open SpringBootCasClientApplication.java and add the following bean definition:

@Bean
public ServiceProperties serviceProperties() {
ServiceProperties serviceProperties = new ServiceProperties();
    serviceProperties.setService("http://localhost:9090/login/cas");
    serviceProperties.setSendRenew(false);
    return serviceProperties;
}

The URL http://localhost:9090/login/cas that is configured will internally get mapped to CasAuthenticationFilter. The parameter sendRenew is set to false. Being set as false, this tells the login service that username/password is required to gain access to the service, every time. It also gives the user access to all services/client without having to enter a username/password (if already done once). When logged out, the user is logged out automatically from all services.