code: @Override
      protected void resolveCredential(final CredentialResolver resolver) {
          resolver.resolve(LocalUserCredential.class, credential -> {
              final LocalUserCredential userCredential = credential;
              final String username = userCredential.getUser();
              final String password = userCredential.getPassword();
              if (!fessConfig.isAdminUser(username)) {
                  final OptionalEntity<FessUser> ldapUser = ComponentUtil.getLdapManager().login(username, password);
                  if (ldapUser.isPresent()) {
                      return ldapUser;
                  }
              }
              return doFindLoginUser(username, encryptPassword(password));
          });
          final LoginCredentialResolver loginResolver = new LoginCredentialResolver(resolver);
          for (final SsoAuthenticator auth : ComponentUtil.getSsoManager().getAuthenticators()) {
              auth.resolveCredential(loginResolver);
          }
      }
docs: ==============