apollo-portal/src/main/java/com/ctrip/framework/apollo/portal/spi/configuration/AuthConfiguration.java/SpringSecurityLDAPAuthAutoConfiguration/ldapContextSource
class SpringSecurityLDAPAuthAutoConfiguration:    @Bean
    @ConditionalOnMissingBean
    public ContextSource ldapContextSource() {
      LdapContextSource source = new LdapContextSource();
      source.setUserDn(this.properties.getUsername());
      source.setPassword(this.properties.getPassword());
      source.setAnonymousReadOnly(this.properties.getAnonymousReadOnly());
      source.setBase(this.properties.getBase());
      source.setUrls(this.properties.determineUrls(this.environment));
      source.setBaseEnvironmentProperties(
          Collections.unmodifiableMap(this.properties.getBaseEnvironment()));
      return source;
    }