GWT遇到意外的异常

Question

我正在研究GWT应用程序。我将项目导入笔记本电脑，因为我昨晚在桌面上进行了处理。但是我现在收到这个错误。

遇到问题：意外异常 有关详细信息，请参阅日志[C：\ Users ---- \ AppData \ Local \ Temp \ enhance7547571277273228846.log]。

我还注意到我的lib文件夹在图标上有一个红色标记，表示存在问题，但它没有指定。

我昨晚在桌面上工作时遇到了这个错误，我设法通过清理项目来修复它。当我现在尝试清理项目时，我得到了同样的错误。

有什么想法吗？

java.lang.RuntimeException: Unexpected exception
at com.google.appengine.tools.enhancer.Enhancer.execute(Enhancer.java:76)
at com.google.appengine.tools.enhancer.Enhance.<init>(Enhance.java:71)
at com.google.appengine.tools.enhancer.Enhance.main(Enhance.java:51)
Caused by: java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at com.google.appengine.tools.enhancer.Enhancer.execute(Enhancer.java:74)
... 2 more
Caused by: org.datanucleus.exceptions.NucleusException: Plugin (Bundle) "org.datanucleus" is already registered. Ensure you dont have multiple JAR versions of the same plugin in the classpath. 
The URL "file:/C:/eclipse/plugins/com.google.appengine.eclipse.sdkbundle_1.7.4/appengine-java-sdk-1.7.4/lib/opt/tools/datanucleus/v2/datanucleus-core-3.1.1.jar" is already registered, and you are trying to register an identical plugin located at URL "file:/C:/eclipse/plugins/com.google.appengine.eclipse.sdkbundle_1.7.4/appengine-java-sdk-1.7.4/lib/opt/user/datanucleus/v1/datanucleus-core-1.1.5.jar."
at org.datanucleus.plugin.NonManagedPluginRegistry.registerBundle(NonManagedPluginRegistry.java:541)
at org.datanucleus.plugin.NonManagedPluginRegistry.registerBundle(NonManagedPluginRegistry.java:395)
at org.datanucleus.plugin.NonManagedPluginRegistry.registerExtensions(NonManagedPluginRegistry.java:219)
at org.datanucleus.plugin.NonManagedPluginRegistry.registerExtensionPoints(NonManagedPluginRegistry.java:160)
at org.datanucleus.plugin.PluginManager.<init>(PluginManager.java:65)
at org.datanucleus.plugin.PluginManager.createPluginManager(PluginManager.java:427)
at org.datanucleus.NucleusContext.<init>(NucleusContext.java:224)
at org.datanucleus.NucleusContext.<init>(NucleusContext.java:204)
at org.datanucleus.enhancer.DataNucleusEnhancer.<init>(DataNucleusEnhancer.java:160)
at org.datanucleus.enhancer.DataNucleusEnhancer.main(DataNucleusEnhancer.java:1133)
... 7 more

我的课程路径

        <?xml version="1.0" encoding="UTF-8"?>
<classpath>
    <classpathentry kind="src" path="src"/>
    <classpathentry kind="src" output="test-classes" path="test"/>
    <classpathentry kind="con" path="com.google.appengine.eclipse.core.GAE_CONTAINER"/>
    <classpathentry kind="con" path="com.google.gwt.eclipse.core.GWT_CONTAINER"/>
    <classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER"/>
    <classpathentry exported="true" kind="lib" path="war/WEB-INF/lib/jsoup-1.7.2.jar"/>
    <classpathentry kind="output" path="war/WEB-INF/classes"/>

</classpath>