defaultMap.put(FessConfig.USE_OWN_TMP_DIR, "true");
            defaultMap.put(FessConfig.MAX_LOG_OUTPUT_LENGTH, "4000");
            defaultMap.put(FessConfig.ADAPTIVE_LOAD_CONTROL, "50");
            defaultMap.put(FessConfig.SUPPORTED_UPLOADED_JS_EXTENTIONS, "js");
            defaultMap.put(FessConfig.SUPPORTED_UPLOADED_CSS_EXTENTIONS, "css");

        allows `tf.Variable`s to be nested in `tf.experimental.ExtensionType`s.
    *   Added a new constructor argument `experimental_enable_variable_lifting`
        to `tf.Variable`, defaulting to True. When it's `False`, the variable
        won't be lifted out of `tf.function`, thus it can be used as a
        `tf.function`-local variable: during each execution of the