Vaadin login page conitiously and automatically reloads with spring-session-jdbc

Question

I've just started to dive into Vaadin UI development, please excuse me in case of any silly mistakes. Can someone please help?

I built a simple sbring-boot application, that uses spring-security for ldap based auth and vaadin for ui. It has 2 pages: login screen and main page.

The WebSecurityConfig.java is:

@EnableWebSecurity
public class WebSecurityConfig extends VaadinWebSecurityConfigurerAdapter {
    @Autowired
    LdapDatasource ldapDatasource;

    @Override
    protected void configure(HttpSecurity http) throws Exception {
        super.configure(http);
        setLoginView(http, LoginScreen.class);
    }

    @Override
    public void configure(WebSecurity web) throws Exception {
        web.ignoring().antMatchers("/img/**");
        super.configure(web);
    }

    @Override
    protected void configure(AuthenticationManagerBuilder auth) throws Exception {
        var provider = ldapDatasource.createAuthProvider();
        auth.authenticationProvider(provider);
    }

}

The AppShell.java is:

@Theme(themeClass = Lumo.class, variant = Lumo.LIGHT)
public class AppShell implements AppShellConfigurator {
}

The Application.java is:

@SpringBootApplication
public class Application {
    public static void main(String[] args) {
        SpringApplication.run(Application.class, args);
    }
}

The build.gradle is:

plugins {
    id 'org.springframework.boot' version '2.6.0'
    id 'io.spring.dependency-management' version '1.0.11.RELEASE'
    id 'java'
    id 'idea'
    id 'war'
    id 'com.vaadin' version "$vaadinVersion"
}

group = 'com.sample'
version = '0.0.1-SNAPSHOT'

repositories {
    mavenCentral()
    maven { url = "https://maven.vaadin.com/vaadin-addons" }
}

dependencies {
    implementation 'com.vaadin:vaadin-spring-boot-starter'
    implementation 'dev.mett.vaadin:tooltip:2.2.0'
    developmentOnly 'org.springframework.boot:spring-boot-devtools'

    implementation 'org.springframework.boot:spring-boot-starter-security'
    implementation 'org.springframework.security:spring-security-ldap'

    implementation 'org.springframework.session:spring-session-jdbc:2.4.2'
    implementation 'org.postgresql:postgresql:42.3.1'

    testImplementation 'org.springframework.boot:spring-boot-starter-test'
    testImplementation 'org.springframework.security:spring-security-test'
}

dependencyManagement {
    imports {
        mavenBom "com.vaadin:vaadin-bom:$vaadinVersion"
        mavenBom 'org.springframework.session:spring-session-bom:2020.0.3'
    }
}


vaadin {
    optimizeBundle = false
    //productionMode = true
}


compileJava {
    options.encoding = 'UTF-8'
}

test {
    useJUnitPlatform()
}

application.properties is empty.

Main page has annotations:

@Route("")
@PageTitle("Main page")
@PermitAll

And login page has annotation:

@Route("login")
@PageTitle("Login")

Everything works fine at this point. App automatically redirects to login page unauthorized users. Custom vaadin login page is displayed. Login through ldap goes completely well. And after login, app proceeds to main page.

But as soon as i try to store session information in PostgreSQL database, with adding file PostgresConfig.java with following contents:

@EnableJdbcHttpSession
public class PostgresConfig {

    @Bean
    public DataSource dataSource() {
        var ds = new PGSimpleDataSource();
        ds.setUrl("jdbc:postgresql://localhost:5432/sample");
        ds.setUser("postgres");
        ds.setPassword("1111");

        return ds;
    }

    @Bean
    public PlatformTransactionManager transactionManager(DataSource dataSource) {
        return new DataSourceTransactionManager(dataSource);
    }
}

vaadin starts endless reloading of login page after app startup.

I've tried to disable vaadin login page, changing:

public class WebSecurityConfig extends VaadinWebSecurityConfigurerAdapter

to

public class WebSecurityConfig extends WebSecurityConfigurerAdapter

and then standard spring-security login page opens fine and i can login. I see session in my postgres database. But when i login, main page goes "Connection lost" and never loads.

There is no point in entire project it reaches during endless reload, except AppShell's configurePage method on every page load.

And i've managed to capture web requests from development console, which happens every page reload:

After that bunch of requests it goes reload all the time. There is no such problem out in google, and reload happens somewhere inside spring/vaadin request filters or in js in my opinion.

What can lead to this behavior?