/** The key of the configuration. e.g. admin */
    String INDEX_USER_initial_password = "index.user.initial_password";

    /** The key of the configuration. e.g. favorite_count */
    String INDEX_FIELD_favorite_count = "index.field.favorite_count";

    /** The key of the configuration. e.g. click_count */
    String INDEX_FIELD_click_count = "index.field.click_count";