This is the main resource server configuration class, where we annotate it with the @EnableResourceServer annotation and extend it from ResourceServerConfigurerAdapter, as shown in the following code snippet:

@Configuration
@EnableResourceServer
public class ResourceServerConfig extends ResourceServerConfigurerAdapter {
  @Autowired
  private CustomAccessTokenConverter customAccessTokenConverter;
  @Override
  public void configure(final HttpSecurity http) throws Exception {
      http.sessionManagement()
        .sessionCreationPolicy(SessionCreationPolicy.ALWAY)
        .and()
        .authorizeRequests().anyRequest().permitAll();
  }
  @Override
  public void configure(final ResourceServerSecurityConfigurer config) {
      config.tokenServices(tokenServices());
  }
  @Bean
  public TokenStore tokenStore() {
      return new JwtTokenStore(accessTokenConverter());
  }
  @Bean
  public JwtAccessTokenConverter accessTokenConverter() {
      final JwtAccessTokenConverter converter = new JwtAccessTokenConverter();
      converter.setAccessTokenConverter(customAccessTokenConverter);
      converter.setSigningKey("secret");
      converter.setVerifierKey("secret");
      return converter;
  }
  @Bean
  @Primary
  public DefaultTokenServices tokenServices() {
      final DefaultTokenServices defaultTokenServices = 
        new DefaultTokenServices();
      defaultTokenServices.setTokenStore(tokenStore());
      return defaultTokenServices;
  }
}