Oracle的IDE-Jdeveloper 竟然有如此搞笑的错误信息，而在Eclipse 命令行OK， 那位使用Jdveloper10的朋友解释一下！

Oracle的IDE-Jdeveloper 竟然有如此搞笑的错误信息，而在Eclipse 命令行OK， 那位使用Jdveloper10的朋友解释一下！

         Jdeveloper 竟然报这样的错误，而在Eclipse 及通过命令行可以执行成功，不知道为什么，那位朋友使用Jdeveloper 帮我看看，呵呵，指不定就是Jdevloper一个Bug。
        这段代码如下：

public   class  TreeClient  {
    public static <T> String toString(Tree<T> t){
       return  t.visit(new Tree.Visitor<T,String>(){
           public String leaf(T e){
           return e.toString();
           }
           public String branch(String l,String r){
           return l.toString()+r.toString();
           }
       });
    }
    public static <N extends Number> Double sum(Tree<N> t){
        return t.visit(new Tree.Visitor<N,Double>(){
             public Double leaf(N e){
             return e.doubleValue();
             }
             public Double branch(Double l,Double r){
             return l+r;
             }
                });

    }
    
    public static void main(String[] args){
        Tree<Integer> t =Tree.branch(Tree.branch(Tree.leaf(1),Tree.leaf(2)),Tree.leaf(3));
        System.out.println(t.toString());
        System.out.println(sum(t));
    }
}
abstract   class  Tree < E >   {

    public interface Visitor<E,R>{
        public R leaf(E elt);
        public R branch(R left,  R righ );
    }

    public abstract <R> R visit(Visitor<E,R> v);
    
    public static <T> Tree<T> leaf(final T e){
        return new Tree<T>(){


                public <R> R visit(Visitor<T,R> v) {
                    return v.leaf(e);
                }
            };
    }
    public static <T> Tree<T> branch(final Tree<T> i,final Tree<T> r){
        return new Tree<T>(){

                public <R> R visit(Visitor<T,R> v) {
                    return v.branch(i.visit(v),r.visit(v));
                }
            };

    }
}

     Jdeveloper10 报：
Error(48,30): method visit(citi.Tree.Visitor<T,R>) in anonymous class cannot override method visit(citi.Tree.Visitor<E,R>) in class citi.Tree with different return type, was
 Error(56,30): method visit(citi.Tree.Visitor<T,R>) in anonymous class cannot override method visit(citi.Tree.Visitor<E,R>) in class citi.Tree with different return type, was

下图所示：


而Eclipse 和命令行都能得到正确的结果 如下图：

  

      那位使用Jdeveloper的朋友解释一下原因？ 我使用的是jdevstudio10132  JDK是Sun 1.5