ask one question about "like/unlike"

[langkins]

pls read the source code as below (from stream example):

public void like(final String post_id, final boolean val) {
    Bundle params = new Bundle();
    if (!val) {
        params.putString("method", "delete");
    }
    getFb().request(post_id + "/likes", new Bundle(), "POST",
            new AsyncRequestListener() {

        public void onComplete(JSONObject response) {
            callJs("javascript:onLike('" + post_id + "'," + val + ")");
        }
    });
}

i do not know why pass a "new Bundle()" not the "params", to the request call.
could you tell me ?thank you.

[langkins]

and i also want to know what is the usage of "method=delete" set to the params.