如何使泛型类型参数包含在内？

I have an interface:

我有一个界面:

  /**
   * Getter for any values within the GameObject and it's subclasses. 
   * Used as callback.
   * 
   * Typical implementation would look like:
   *   new ValueGetter<SummonerSpell, String> {
   *     public String getValue(SummonerSpell source) {
   *       return source.toString();
   *     }
   *   }
   * @param <T> 
   * @param <V> Type of value retrieved
   */
  public static interface ValueGetter<T extends GameObject, V> {
    public V getValue(T source);
  }
  /**
   * Get