docs: private Map<String, String> subPropertyMap(String configPrefix, Map propertiesMap) {
          Map<String, String> config = new HashMap<String, String>();
          for (Object o : propertiesMap.keySet()) {
              String key = (String) o;
              if (key.startsWith(configPrefix)) {
                  String conf = key.substring(configPrefix.length());
                  config.put(conf, propertiesMap.get(key).toString());
              }
          }
          return config;
      }