gwt-2.7.0升级 - GWT构建错误'com.google.gwt.user.cellview.client.CellBasedWidgetImpl'不能是抽象的

Question

[java]    [ERROR] Errors in 'com/google/gwt/user/client/DOM.java'
[java]       [ERROR] Line 64: Rebind result 'com.google.gwt.user.client.impl.DOMImpl' cannot be abstract

。 。 。 。 。

   java.util.Set
 [java]                                                                                                                                                                                                    Verifying instantiability
 [java]                                                                                                                                                                                                       java.util.LinkedHashSet<?>
 [java]                                                                                                                                                                                                          [WARN] Checking all subtypes of Object which qualify for serialization
 [java]    [ERROR] Errors in 'com/google/gwt/user/cellview/client/CellBasedWidgetImpl.java'
 [java]       [ERROR] Line 46: Rebind result 'com.google.gwt.user.cellview.client.CellBasedWidgetImpl' cannot be abstract

使用ant（gwt-2.7.0）构建gwt项目战时出错。项目在超级开发模式下运行正常。使用gwt-2.5.0构建战争没有任何错误