code>request</code>.
            @throws <code>Error</code> if unable to determine the file type by its extention.
            @example
                <code>
                    this._groupLoad = new GroupLoad();
                    this._groupLoad.addLoad(LoadItemUtil.createLoadItem("test.flv"));
                    this._groupLoad.addLoad(LoadItemUtil.createLoadItem("test.xml"));
                    this._groupLoad.addLoad(LoadItemUtil.createLoadItem("test.mp3"));
                    this._groupLoad.addL