title: obtain request parameter in Spring security Filter
body: <p>Can someone help in in obtaining request parameter 
  in WebsecurityConfig Httpsecurity configure method ? I need to extract the request parameter in the below case acr=loa3 that is coming from request</p>
  
  <pre><code>@Configuration
  @EnableWebSecurity
  public class WebSecurityConfig extends WebSecurityConfigurerAdapter {
      @Override
      protected void configure(HttpSecurity http) throws Exception {
          http.sessionManagement()
              .maximumSessions(1)
              .expiredUrl(this.uiUri + "/expired")
              .maxSessionsPreventsLogin(true)
              .and()
              .invalidSessionUrl(this.uiUri + "/expired")
              .and()
              .csrf().disable().cors()
              .and()       
              .authorizeRequests()
              .antMatchers("/expired").permitAll()
              .anyRequest().authenticated()
              .and()
  //Can some one help me here on how to extract request param coming in the url for example xyz.com/login?acr=loa3 ? I need to send that as acr value before the configureOIDCfilter executes
              .addFilterBefore(configureOIDCfilter(http, acrValue), 
                               AbstractPreAuthenticatedProcessingFilter.class)
              .exceptionHandling().authenticationEntryPoint(new LoginUrlAuthenticationEntryPoint(this.redirectUri));
      }
  }
  @Bean
      public OIDCAuthenticationFilter configureOIDCfilter(HttpSecurity http, String acrValue) throws Exception {
  
          OIDCAuthenticationFilter filter = new OIDCAuthenticationFilter();
          StaticSingleIssuerService issuerService = new StaticSingleIssuerService();
          issuerService.setIssuer(issuerUrl);
          filter.setServerConfigurationService(new DynamicServerConfigurationService());
          StaticClientConfigurationService clientService = new StaticClientConfigurationService();
          RegisteredClient client = new RegisteredClient();
          client.setClientId(clientId);
          client.setDefaultACRvalues(ImmutableSet.of(acrValue));
          return filter;
  
      }
  </code></pre>