code: public Set<String> keySet() throws IOException {
      Set<String> ret = new HashSet<>();
      JsonParser p = this.getParser();
      JsonToken t;
  
      t = p.nextToken();
  
      while (t != null) {
        if (t == JsonToken.FIELD_NAME) {
          ret.add(p.getCurrentName());
        }
        t = p.nextToken();
      }
      p.close();
      return ret;
    }
docs: Return a set of all key names in the component
  
  @return the set of key names
  @throws IOException if there is an I/O error