docs: public Properties getProperties(String pGroupKey) {
      // Stupid impl...
      XMLProperties props    = new XMLProperties();
      String        groupKey = pGroupKey;
  
      if (groupKey.charAt(groupKey.length()) != '.') {
        groupKey += ".";
      }
  
      Iterator iterator = entrySet().iterator();
  
      while (iterator.hasNext()) {
        Map.Entry entry = (Map.Entry) iterator.next();
        String    key   = (String) entry.getKey();
  
        if (key.startsWith(groupKey)) {
          String subKey = key.substring(key.indexOf(groupKey));
  
          props.setPropertyValue(subKey, entry.getValue());
        }
      }
  
      return ((props.size() > 0) ? props : null);
    }