docs: function StringToStringStatesConverter(config) {
    StringToStringStatesConverter.super_.call(this, config);
  
    // Check the configuration.
    if (!this.config.length || typeof this.config.length !== "number") {
      this.config.length = 1;
    }
    if (!this.config.lookbackLength || typeof this.config.lookbackLength !== "number") {
      this.config.lookbackLength = 0;
    }
  }