getConfig(key, defaultValue = undefined) {
    const value = _.get(this.config, key, defaultValue);

    if (value === null) {
      return defaultValue;
    }

    return value;
  }
Provide the configuration inside "conf.json" with a comma separated access for array structures

@param key eg "webserver.port" nested config supported
@param defaultValue value if config does not exists
@returns {*}