public OAuthBearerToken token() {
        return token;
    }
@Test
    public void testToken() {
        OAuthBearerTokenCallback callback = new OAuthBearerTokenCallback();
        callback.token(TOKEN);
        assertSame(TOKEN, callback.token());
        assertNull(callback.errorCode());
        assertNull(callback.errorDescription());
        assertNull(callback.errorUri());
    }