我创建了一个PHP Liferay Portlet，在portlet.xml中我添加了这个类：
<portlet-class>com.liferay.util.bridges.php.PHPPortlet</portlet-class>
当我部署portlet时，我收到此错误：
com.liferay.portal.kernel.deploy.hot.HotDeployException: Error registering portlets for nsFileUpload-portletnsFileUpload-portlet
at com.liferay.portal.kernel.deploy.hot.BaseHotDeployListener.throwHotDeployException(BaseHotDeployListener.java:46)
at com.liferay.portal.deploy.hot.PortletHotDeployListener.invokeDeploy(PortletHotDeployListener.java:127)
at com.liferay.portal.deploy.hot.HotDeployImpl.doFireDeployEvent(HotDeployImpl.java:205)
at com.liferay.portal.deploy.hot.HotDeployImpl.fireDeployEvent(HotDeployImpl.java:96)
at com.liferay.portal.kernel.deploy.hot.HotDeployUtil.fireDeployEvent(HotDeployUtil.java:27)
at com.liferay.portal.kernel.servlet.PluginContextListener.fireDeployEvent(PluginContextListener.java:164)
at com.liferay.portal.kernel.servlet.PluginContextListener.doPortalInit(PluginContextListener.java:154)
at com.liferay.portal.kernel.util.BasePortalLifecycle.portalInit(BasePortalLifecycle.java:44)
at com.liferay.portal.kernel.util.PortalLifecycleUtil.register(PortalLifecycleUtil.java:64)
at com.liferay.portal.kernel.util.PortalLifecycleUtil.register(PortalLifecycleUtil.java:56)
at com.liferay.portal.kernel.util.BasePortalLifecycle.registerPortalLifecycle(BasePortalLifecycle.java:54)
at com.liferay.portal.kernel.servlet.PluginContextListener.contextInitialized(PluginContextListener.java:116)
at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4939)
at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5434)
at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:901)
at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:877)
at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:633)
at org.apache.catalina.startup.HostConfig.deployDirectory(HostConfig.java:1113)
at org.apache.catalina.startup.HostConfig$DeployDirectory.run(HostConfig.java:1671)
at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
at java.util.concurrent.FutureTask.run(FutureTask.java:138)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
at java.lang.Thread.run(Thread.java:662)
Caused by: java.lang.NoClassDefFoundError: com/caucho/vfs/Path
at java.lang.Class.getDeclaredConstructors0(Native Method)
at java.lang.Class.privateGetDeclaredConstructors(Class.java:2389)
at java.lang.Class.getConstructor0(Class.java:2699)
at java.lang.Class.newInstance0(Class.java:326)
at java.lang.Class.newInstance(Class.java:308)
at com.liferay.portlet.PortletBagFactory.getPortletInstance(PortletBagFactory.java:418)
at com.liferay.portlet.PortletBagFactory.create(PortletBagFactory.java:121)
at com.liferay.portal.deploy.hot.PortletHotDeployListener.doInvokeDeploy(PortletHotDeployListener.java:369)
at com.liferay.portal.deploy.hot.PortletHotDeployListener.invokeDeploy(PortletHotDeployListener.java:124)
... 24 more
Caused by: java.lang.ClassNotFoundException: com.caucho.vfs.Path
这意味着找不到从com.caucho.vfs.Path（Source）导入的课程ServletContextPath.java。
我该如何解决这个问题？我需要导入那个类吗？