Eclipse luna到Eclipse 2018的迁移问题。
切换到Java jdk8编译器。我遇到很多导入问题，例如javax。另外，从appengine sdk迁移到Google Cloud时，转换为appengine项目失败，并显示以下错误：发生了问题
Bundle: org.eclipse.jface 3.14.0.v20180423-0714
Message: java.lang.RuntimeException: java.lang.NullPointerException
Exception:
java.lang.RuntimeException: java.lang.NullPointerException
at org.eclipse.wst.common.project.facet.ui.internal.RuntimesPropertyPage.performOk(RuntimesPropertyPage.java:207)
at org.eclipse.jface.preference.PreferenceDialog$7.run(PreferenceDialog.java:902)
at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:42)
at org.eclipse.ui.internal.JFaceUtil.lambda$0(JFaceUtil.java:44)
at org.eclipse.jface.util.SafeRunnable.run(SafeRunnable.java:173)
at org.eclipse.jface.preference.PreferenceDialog.okPressed(PreferenceDialog.java:886)
at org.eclipse.ui.internal.dialogs.FilteredPreferenceDialog.okPressed(FilteredPreferenceDialog.java:484)
at org.eclipse.jface.preference.PreferenceDialog.buttonPressed(PreferenceDialog.java:230)
at org.eclipse.jface.dialogs.Dialog.lambda$0(Dialog.java:619)
at org.eclipse.swt.events.SelectionListener$1.widgetSelected(SelectionListener.java:81)
at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:249)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:86)
at org.eclipse.swt.widgets.Display.sendEvent(Display.java:4118)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1052)
at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:3931)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3534)
at org.eclipse.jface.window.Window.runEventLoop(Window.java:818)
at org.eclipse.jface.window.Window.open(Window.java:794)
at org.eclipse.ui.dialogs.PropertyDialogAction.run(PropertyDialogAction.java:157)
at org.eclipse.jface.action.Action.runWithEvent(Action.java:473)
at org.eclipse.jface.action.ActionContributionItem.handleWidgetSelection(ActionContributionItem.java:565)
at org.eclipse.jface.action.ActionContributionItem.lambda$4(ActionContributionItem.java:397)
at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:86)
at org.eclipse.swt.widgets.Display.sendEvent(Display.java:4118)
at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1052)
at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:3931)
at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3534)
at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$5.run(PartRenderingEngine.java:1170)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:336)
at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:1059)
at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:153)
at org.eclipse.ui.internal.Workbench.lambda$3(Workbench.java:667)
at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:336)
at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:597)
at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:148)
at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:152)
at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:134)
at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:104)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:388)
at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:243)
at sun.reflect.NativeMethodAccessorImpl.invoke0(null:-2)
at sun.reflect.NativeMethodAccessorImpl.invoke(null:-1)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(null:-1)
at java.lang.reflect.Method.invoke(null:-1)
at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:656)
at org.eclipse.equinox.launcher.Main.basicRun(Main.java:592)
at org.eclipse.equinox.launcher.Main.run(Main.java:1498)
caused by java.lang.NullPointerException: null
at org.eclipse.wst.common.project.facet.ui.internal.RuntimesPropertyPage$4.run(RuntimesPropertyPage.java:161)
at org.eclipse.core.internal.resources.Workspace.run(Workspace.java:2289)
at org.eclipse.core.internal.resources.Workspace.run(Workspace.java:2316)
at org.eclipse.wst.common.project.facet.ui.internal.RuntimesPropertyPage$5.run(RuntimesPropertyPage.java:175)
at org.eclipse.jface.operation.ModalContext$ModalContextThread.run(ModalContext.java:119)