docs: public String getPublicConfigValue(String key) throws ConfigurationException {
          if (!allProps.containsKey(key)) {
              throw new UndefinedPropertyException("The requested config key does not exist.");
          }
          if (restrictedConfigs.contains(key)) {
              throw new ConfigurationException("The requested config key is not publicly available!");
          }
          return allProps.get(key);
      }