/** The underlying index update callback to delegate operations to. */
    protected IndexUpdateCallback indexUpdateCallback;

    /** Factory for creating crawler clients to handle different URL schemes. */
    protected CrawlerClientFactory crawlerClientFactory;

    /** List of URLs to be deleted, cached for batch processing. */
    protected List<String> deleteUrlList = new ArrayList<>(100);

Use `Response.challenges()` to get the schemes and realms of any authentication challenges. When fulfilling a `Basic` challenge, use `Credentials.basic(username, password)` to encode the request header.

=== ":material-language-kotlin: Kotlin"
    ```kotlin

        #  This is only for the main schema. Additional schemas are unconcerned.
        #
        #; columnExceptMap = map:{
        #    ; FOO_TABLE = list:{FOO_COLUMN ; prefix:FOO_ ; suffix:_FOO ; contain:_FOO_}
        #}

        # o additionalSchemaMap: (NotRequired - Default map:{})
        #  If you want to include other schemas in generating target,
        #  you should specify the map of included schemas.

        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    Unauthorized:
      description: Unauthorized request
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'
    NotFound:
      description: Page not found
      content:
        application/json:
          schema:
            $ref: '#/components/schemas/Error'

    #   o schema: (Required: if empty schema means valid schema, not required)
    #   o user: (NotRequired - Default same as main schema)
    #   o password: (NotRequired - Default same as main schema)
    #   o propertiesMap: (NotRequired - Default map:{})
    #   o objectTypeTargetList: (NotRequired - Default list{TABLE;VIEW})
    #
    #; additionalDropMapList = list:{
    #    ; map:{

jflute <******@****.***> 1437804256 +0900

                final String scheme = paramMap.get(CRAWLER_WEB_AUTH + "." + webAuthName + ".scheme");

                final AuthScheme authScheme = getAuthScheme(paramMap, webAuthName, scheme);
                final AuthScope authScope = getAuthScope(webAuthName, scheme, paramMap);
                final Credentials credentials = getCredentials(webAuthName, scheme, paramMap);

  @ArgumentsSource(TestDataParamProvider::class)
  @ParameterizedTest
  fun httpUrl(testData: WebPlatformUrlTestData) {
    if (!testData.scheme.isEmpty() && !HTTP_URL_SCHEMES.contains(testData.scheme)) {
      System.err.println("Ignoring unsupported scheme ${testData.scheme}")
      return
    }

    if (!testData.base!!.startsWith("https:") &&
      !testData.base!!.startsWith("http:") &&

            proxyAddress.port,
            url.scheme,
            challenge.realm,
            challenge.scheme,
            url.toUrl(),
            Authenticator.RequestorType.PROXY,
          )
        } else {
          Authenticator.requestPasswordAuthentication(
            url.host,
            proxy.connectToInetAddress(url, dns),
            url.port,
            url.scheme,
            challenge.realm,

    authParams["charset"] = charset.name()
    return Challenge(scheme, authParams)
  }

  @JvmName("-deprecated_scheme")
  @Deprecated(
    message = "moved to val",
    replaceWith = ReplaceWith(expression = "scheme"),
    level = DeprecationLevel.ERROR,
  )
  fun scheme(): String = scheme

  @JvmName("-deprecated_authParams")
  @Deprecated(
    message = "moved to val",