Unable to generate tables from entities

org.eclipse.e4.core.di.InjectionException: java.lang.IllegalArgumentException: Argument cannot be null
	at org.eclipse.e4.core.internal.di.MethodRequestor.execute(MethodRequestor.java:62)
	at org.eclipse.e4.core.internal.di.InjectorImpl.invokeUsingClass(InjectorImpl.java:247)
	at org.eclipse.e4.core.internal.di.InjectorImpl.invoke(InjectorImpl.java:229)
	at org.eclipse.e4.core.contexts.ContextInjectionFactory.invoke(ContextInjectionFactory.java:132)
	at org.eclipse.e4.core.commands.internal.HandlerServiceHandler.execute(HandlerServiceHandler.java:149)
	at org.eclipse.core.commands.Command.executeWithChecks(Command.java:499)
	at org.eclipse.core.commands.ParameterizedCommand.executeWithChecks(ParameterizedCommand.java:508)
	at org.eclipse.e4.core.commands.internal.HandlerServiceImpl.executeHandler(HandlerServiceImpl.java:210)
	at org.eclipse.e4.ui.workbench.renderers.swt.HandledContributionItem.executeItem(HandledContributionItem.java:825)
	at org.eclipse.e4.ui.workbench.renderers.swt.HandledContributionItem.handleWidgetSelection(HandledContributionItem.java:701)
	at org.eclipse.e4.ui.workbench.renderers.swt.HandledContributionItem.access$6(HandledContributionItem.java:685)
	at org.eclipse.e4.ui.workbench.renderers.swt.HandledContributionItem$4.handleEvent(HandledContributionItem.java:613)
	at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
	at org.eclipse.swt.widgets.Display.sendEvent(Display.java:4188)
	at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1467)
	at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1490)
	at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1475)
	at org.eclipse.swt.widgets.Widget.notifyListeners(Widget.java:1279)
	at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:4031)
	at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3658)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$9.run(PartRenderingEngine.java:1151)
	at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:1032)
	at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:148)
	at org.eclipse.ui.internal.Workbench$5.run(Workbench.java:636)
	at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332)
	at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:579)
	at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:150)
	at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:135)
	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:380)
	at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:235)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:606)
	at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:648)
	at org.eclipse.equinox.launcher.Main.basicRun(Main.java:603)
	at org.eclipse.equinox.launcher.Main.run(Main.java:1465)
Caused by: java.lang.IllegalArgumentException: Argument cannot be null
	at org.eclipse.swt.SWT.error(SWT.java:4422)
	at org.eclipse.swt.SWT.error(SWT.java:4356)
	at org.eclipse.swt.SWT.error(SWT.java:4327)
	at org.eclipse.swt.widgets.Widget.error(Widget.java:783)
	at org.eclipse.swt.widgets.Combo.setText(Combo.java:1725)
	at org.eclipse.jdt.internal.ui.wizards.dialogfields.ComboDialogField.getComboControl(ComboDialogField.java:120)
	at org.eclipse.jdt.internal.ui.wizards.dialogfields.ComboDialogField.doFillIntoGrid(ComboDialogField.java:56)
	at org.jboss.tools.hibernate.jpt.ui.wizard.GenerateInitWizardPage.createControl(GenerateInitWizardPage.java:163)
	at org.eclipse.jface.wizard.Wizard.createPageControls(Wizard.java:178)
	at org.eclipse.jface.wizard.WizardDialog.createPageControls(WizardDialog.java:759)
	at org.eclipse.jface.wizard.WizardDialog.createContents(WizardDialog.java:622)
	at org.eclipse.jface.window.Window.create(Window.java:435)
	at org.eclipse.jface.dialogs.Dialog.create(Dialog.java:1101)
	at org.eclipse.jface.window.Window.open(Window.java:797)
	at org.jboss.tools.hibernate.jpt.ui.internal.platform.HibernateJpaPlatformUi.generateDDL(HibernateJpaPlatformUi.java:64)
	at org.eclipse.jpt.jpa.ui.internal.handlers.GenerateDDLHandler.generateDDL(GenerateDDLHandler.java:45)
	at org.eclipse.jpt.jpa.ui.internal.handlers.GenerateDDLHandler.execute(GenerateDDLHandler.java:37)
	at org.eclipse.ui.internal.handlers.HandlerProxy.execute(HandlerProxy.java:294)
	at org.eclipse.ui.internal.handlers.E4HandlerProxy.execute(E4HandlerProxy.java:90)
	at sun.reflect.GeneratedMethodAccessor179.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:606)
	at org.eclipse.e4.core.internal.di.MethodRequestor.execute(MethodRequestor.java:55)
	... 40 more