code: public void addRequestProp(String key, Object value) {
          if (key == null || value == null) {
              return;
          }
          if (requestProps == null) {
              requestProps = new HashMap<String, Object>(16);
          }
          requestProps.put(key, value);
      }
docs: Add request prop.
  
  @param key   the key
  @param value the value