code: public void storeFlattened(OutputStream out) throws IOException {
          Properties p = new Properties();
          for (String key : keySet()) {
              if (!p.containsKey(key)) {
                  p.setProperty(key, get(key));
              }
          }
  
          p.store(out, null);
      }
docs: Store all properties, those local and also those in parent props
  
  @param out
  The stream to write to
  @throws IOException
  If there is an error writing