eclipse - Spring Tool Suite: NullpointerException at "Push In" operation -

i used spring tool suite spring roo reverse engineer database. want remove aspectj files project , obtain standard javaee classes. so, did right click on project --> refactor --> push in... after this, error box saying multiple problems have occurred (java.lang.nullpointerexception). spring tool suite freezes , have close task manager. in error log found following error on , on again, seems occur every 20 milliseconds. occurs when select few classes , not whole project. appreciate, if me solving problem.

here exception logfile:

!message problems occurred when invoking code plug-in: "org.eclipse.jface". !stack 0 java.lang.nullpointerexception     @ org.eclipse.ajdt.internal.ui.refactoring.pushinrefactoringinputpage$3.update(pushinrefactoringinputpage.java:314)     @ org.eclipse.jface.viewers.viewercolumn.refresh(viewercolumn.java:141)     @ org.eclipse.jface.viewers.abstracttableviewer.doupdateitem(abstracttableviewer.java:382)     @ org.eclipse.jface.viewers.structuredviewer$updateitemsaferunnable.run(structuredviewer.java:474)     @ org.eclipse.core.runtime.saferunner.run(saferunner.java:42)     @ org.eclipse.ui.internal.jfaceutil$1.run(jfaceutil.java:50)     @ org.eclipse.jface.util.saferunnable.run(saferunnable.java:173)     @ org.eclipse.jface.viewers.structuredviewer.updateitem(structuredviewer.java:2170)     @ org.eclipse.jface.viewers.abstracttableviewer.createitem(abstracttableviewer.java:273)     @ org.eclipse.jface.viewers.abstracttableviewer.internalrefreshall(abstracttableviewer.java:715)     @ org.eclipse.jface.viewers.abstracttableviewer.internalrefresh(abstracttableviewer.java:607)     @ org.eclipse.jface.viewers.abstracttableviewer.internalrefresh(abstracttableviewer.java:599)     @ org.eclipse.jface.viewers.abstracttableviewer.lambda$0(abstracttableviewer.java:561)     @ org.eclipse.jface.viewers.structuredviewer.preservingselection(structuredviewer.java:1458)     @ org.eclipse.jface.viewers.structuredviewer.preservingselection(structuredviewer.java:1419)     @ org.eclipse.jface.viewers.abstracttableviewer.inputchanged(abstracttableviewer.java:561)     @ org.eclipse.jface.viewers.contentviewer.setinput(contentviewer.java:286)     @ org.eclipse.jface.viewers.structuredviewer.setinput(structuredviewer.java:1696)     @ org.eclipse.ajdt.internal.ui.refactoring.pushinrefactoringinputpage.createtable(pushinrefactoringinputpage.java:229)     @ org.eclipse.ajdt.internal.ui.refactoring.pushinrefactoringinputpage.createcontrol(pushinrefactoringinputpage.java:172)     @ org.eclipse.ltk.internal.ui.refactoring.refactoringwizarddialog2.createcontents(refactoringwizarddialog2.java:625)     @ org.eclipse.jface.window.window.create(window.java:426)     @ org.eclipse.jface.dialogs.dialog.create(dialog.java:1095)     @ org.eclipse.ltk.ui.refactoring.refactoringwizardopenoperation$1.run(refactoringwizardopenoperation.java:179)     @ org.eclipse.swt.custom.busyindicator.showwhile(busyindicator.java:70)     @ org.eclipse.ltk.ui.refactoring.refactoringwizardopenoperation.run(refactoringwizardopenoperation.java:203)     @ org.eclipse.ltk.ui.refactoring.refactoringwizardopenoperation.run(refactoringwizardopenoperation.java:122)     @ org.eclipse.ajdt.internal.ui.refactoring.pushinrefactoringaction.run(pushinrefactoringaction.java:84)     @ org.eclipse.ajdt.internal.ui.refactoring.pushinrefactoringaction.run(pushinrefactoringaction.java:60)     @ org.eclipse.ui.internal.pluginaction.runwithevent(pluginaction.java:247)     @ org.eclipse.jface.action.actioncontributionitem.handlewidgetselection(actioncontributionitem.java:565)     @ org.eclipse.jface.action.actioncontributionitem.lambda$4(actioncontributionitem.java:397)     @ org.eclipse.swt.widgets.eventtable.sendevent(eventtable.java:84)     @ org.eclipse.swt.widgets.display.sendevent(display.java:4410)     @ org.eclipse.swt.widgets.widget.sendevent(widget.java:1079)     @ org.eclipse.swt.widgets.display.rundeferredevents(display.java:4228)     @ org.eclipse.swt.widgets.display.readanddispatch(display.java:3816)     @ org.eclipse.e4.ui.internal.workbench.swt.partrenderingengine$4.run(partrenderingengine.java:1121)     @ org.eclipse.core.databinding.observable.realm.runwithdefault(realm.java:336)     @ org.eclipse.e4.ui.internal.workbench.swt.partrenderingengine.run(partrenderingengine.java:1022)     @ org.eclipse.e4.ui.internal.workbench.e4workbench.createandrunui(e4workbench.java:150)     @ org.eclipse.ui.internal.workbench$5.run(workbench.java:687)     @ org.eclipse.core.databinding.observable.realm.runwithdefault(realm.java:336)     @ org.eclipse.ui.internal.workbench.createandrunworkbench(workbench.java:604)     @ org.eclipse.ui.platformui.createandrunworkbench(platformui.java:148)     @ org.eclipse.ui.internal.ide.application.ideapplication.start(ideapplication.java:138)     @ org.eclipse.equinox.internal.app.eclipseapphandle.run(eclipseapphandle.java:196)     @ org.eclipse.core.runtime.internal.adaptor.eclipseapplauncher.runapplication(eclipseapplauncher.java:134)     @ org.eclipse.core.runtime.internal.adaptor.eclipseapplauncher.start(eclipseapplauncher.java:104)     @ org.eclipse.core.runtime.adaptor.eclipsestarter.run(eclipsestarter.java:388)     @ org.eclipse.core.runtime.adaptor.eclipsestarter.run(eclipsestarter.java:243)     @ sun.reflect.nativemethodaccessorimpl.invoke0(native method)     @ sun.reflect.nativemethodaccessorimpl.invoke(unknown source)     @ sun.reflect.delegatingmethodaccessorimpl.invoke(unknown source)     @ java.lang.reflect.method.invoke(unknown source)     @ org.eclipse.equinox.launcher.main.invokeframework(main.java:673)     @ org.eclipse.equinox.launcher.main.basicrun(main.java:610)     @ org.eclipse.equinox.launcher.main.run(main.java:1519)