code: public void addParameter(String key, Object value) {
      if (key != null) {
        Map<String, Object> params = getParameters();
        if (value == null) params.remove(key);
        else params.put(key, value);
      }
    }
docs: Adds the given key and value to this component's own parameter.
  <p/>
  If the provided key is <tt>null</tt> nothing happens. If the provided value is <tt>null</tt>
  any existing parameter with the given key name is removed.
  
  @param key
  the key of the new parameter to add.
  @param value
  the value assoicated with the key.