SWT Resource was not properly disposed for custom Font in OutlineView

Using a custom font in the LabelProvider causes an 'SWT Resource was not properly disposed' error in Eclipse.

Here the LabelProvider:

@Inject
protected StylerFactory stylerFactory;

protected Styler keywordStyler = null;

def StyledString text(Import im) {
    val txt = new StyledString("import model ")
    txt.setStyle(0, 12, getKeywordStyler())
    return txt
}

def protected Styler getKeywordStyler() {
    if (keywordStyler===null) {
	    var font = JFaceResources.getFontDescriptor(JFaceResources.TEXT_FONT)
	    var boldFont = font.setStyle(SWT.BOLD)
	    keywordStyler = stylerFactory.createStyler(boldFont, KEYWORD_COLOR, null)
    }
    return keywordStyler
}

After opening and closing the Outline View and running the GC, the console outputs the stacktrace below. Do you know if this can cause a SWT handle leak ?

!MESSAGE Not properly disposed SWT resource
!STACK 0
java.lang.Error: SWT Resource was not properly disposed
	at org.eclipse.swt.graphics.Resource.initNonDisposeTracking(Resource.java:172)
	at org.eclipse.swt.graphics.Resource.<init>(Resource.java:120)
	at org.eclipse.swt.graphics.Font.<init>(Font.java:111)
	at org.eclipse.jface.resource.ArrayFontDescriptor.createFont(ArrayFontDescriptor.java:78)
	at org.eclipse.xtext.ui.label.StylerFactory$DefaultFontStyler.applyStyles(StylerFactory.java:119)
	at org.eclipse.jface.viewers.StyledString.createStyleRange(StyledString.java:475)
	at org.eclipse.jface.viewers.StyledString.getStyleRanges(StyledString.java:439)
	at org.eclipse.jface.viewers.DelegatingStyledCellLabelProvider.update(DelegatingStyledCellLabelProvider.java:113)
	at org.eclipse.jface.viewers.ViewerColumn.refresh(ViewerColumn.java:144)
	at org.eclipse.jface.viewers.AbstractTreeViewer.doUpdateItem(AbstractTreeViewer.java:957)
	at org.eclipse.jface.viewers.AbstractTreeViewer$UpdateItemSafeRunnable.run(AbstractTreeViewer.java:126)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:45)
	at org.eclipse.jface.util.SafeRunnable.run(SafeRunnable.java:174)
	at org.eclipse.jface.viewers.AbstractTreeViewer.doUpdateItem(AbstractTreeViewer.java:1035)
	at org.eclipse.jface.viewers.StructuredViewer$UpdateItemSafeRunnable.run(StructuredViewer.java:427)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:45)
	at org.eclipse.jface.util.SafeRunnable.run(SafeRunnable.java:174)
	at org.eclipse.jface.viewers.StructuredViewer.updateItem(StructuredViewer.java:2109)
	at org.eclipse.jface.viewers.AbstractTreeViewer.updateChildren(AbstractTreeViewer.java:2778)
	at org.eclipse.jface.viewers.AbstractTreeViewer.internalRefreshStruct(AbstractTreeViewer.java:1958)
	at org.eclipse.jface.viewers.TreeViewer.internalRefreshStruct(TreeViewer.java:677)
	at org.eclipse.jface.viewers.AbstractTreeViewer.internalRefreshStruct(AbstractTreeViewer.java:1964)
	at org.eclipse.jface.viewers.TreeViewer.internalRefreshStruct(TreeViewer.java:677)
	at org.eclipse.jface.viewers.AbstractTreeViewer.internalRefresh(AbstractTreeViewer.java:1934)
	at org.eclipse.jface.viewers.AbstractTreeViewer.internalRefresh(AbstractTreeViewer.java:1891)
	at org.eclipse.jface.viewers.AbstractTreeViewer.internalRefresh(AbstractTreeViewer.java:1877)
	at org.eclipse.jface.viewers.StructuredViewer.lambda$2(StructuredViewer.java:1459)
	at org.eclipse.jface.viewers.StructuredViewer.preservingSelection(StructuredViewer.java:1398)
	at org.eclipse.jface.viewers.TreeViewer.preservingSelection(TreeViewer.java:363)
	at org.eclipse.jface.viewers.StructuredViewer.preservingSelection(StructuredViewer.java:1359)
	at org.eclipse.jface.viewers.StructuredViewer.refresh(StructuredViewer.java:1459)
	at org.eclipse.jface.viewers.ColumnViewer.refresh(ColumnViewer.java:526)
	at org.eclipse.jface.viewers.StructuredViewer.refresh(StructuredViewer.java:1418)
	at org.eclipse.xtext.ui.editor.outline.actions.IOutlineContribution$Composite.register(IOutlineContribution.java:74)
	at org.eclipse.xtext.ui.editor.outline.impl.OutlinePage.configureActions(OutlinePage.java:201)
	at org.eclipse.xtext.ui.editor.outline.impl.OutlinePage.createControl(OutlinePage.java:107)
	at org.eclipse.etrice.core.ui.outline.RoomOutlinePage.createControl(RoomOutlinePage.java:39)
	at org.eclipse.ui.views.contentoutline.ContentOutline.doCreatePage(ContentOutline.java:141)
	at org.eclipse.ui.part.PageBookView.createPage(PageBookView.java:369)
	at org.eclipse.ui.part.PageBookView.partActivated(PageBookView.java:696)
	at org.eclipse.ui.views.contentoutline.ContentOutline.partBroughtToTop(ContentOutline.java:205)
	at org.eclipse.ui.part.PageBookView$1.partBroughtToTop(PageBookView.java:1011)
	at org.eclipse.ui.internal.WorkbenchPage$16.run(WorkbenchPage.java:5137)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:45)
	at org.eclipse.ui.internal.WorkbenchPage.firePartBroughtToTop(WorkbenchPage.java:5134)
	at org.eclipse.ui.internal.WorkbenchPage$E4PartListener.partBroughtToTop(WorkbenchPage.java:226)
	at org.eclipse.e4.ui.internal.workbench.PartServiceImpl$6.run(PartServiceImpl.java:313)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:45)
	at org.eclipse.e4.ui.internal.workbench.PartServiceImpl.firePartBroughtToTop(PartServiceImpl.java:310)
	at org.eclipse.e4.ui.internal.workbench.PartServiceImpl.lambda$0(PartServiceImpl.java:106)
	at org.eclipse.e4.ui.services.internal.events.UIEventHandler.lambda$0(UIEventHandler.java:38)
	at org.eclipse.swt.widgets.Synchronizer.syncExec(Synchronizer.java:236)
	at org.eclipse.ui.internal.UISynchronizer.syncExec(UISynchronizer.java:133)
	at org.eclipse.swt.widgets.Display.syncExec(Display.java:4770)
	at org.eclipse.e4.ui.workbench.swt.DisplayUISynchronize.syncExec(DisplayUISynchronize.java:34)
	at org.eclipse.e4.ui.services.internal.events.UIEventHandler.handleEvent(UIEventHandler.java:38)
	at org.eclipse.equinox.internal.event.EventHandlerWrapper.handleEvent(EventHandlerWrapper.java:205)
	at org.eclipse.equinox.internal.event.EventHandlerTracker.dispatchEvent(EventHandlerTracker.java:203)
	at org.eclipse.equinox.internal.event.EventHandlerTracker.dispatchEvent(EventHandlerTracker.java:1)
	at org.eclipse.osgi.framework.eventmgr.EventManager.dispatchEvent(EventManager.java:228)
	at org.eclipse.osgi.framework.eventmgr.ListenerQueue.dispatchEventSynchronous(ListenerQueue.java:151)
	at org.eclipse.equinox.internal.event.EventAdminImpl.dispatchEvent(EventAdminImpl.java:133)
	at org.eclipse.equinox.internal.event.EventAdminImpl.sendEvent(EventAdminImpl.java:75)
	at org.eclipse.equinox.internal.event.EventComponent.sendEvent(EventComponent.java:44)
	at org.eclipse.e4.ui.services.internal.events.EventBroker.send(EventBroker.java:55)
	at org.eclipse.e4.ui.internal.workbench.UIEventPublisher.notifyChanged(UIEventPublisher.java:63)
	at org.eclipse.emf.common.notify.impl.BasicNotifierImpl.eNotify(BasicNotifierImpl.java:424)
	at org.eclipse.e4.ui.model.application.ui.impl.ElementContainerImpl.setSelectedElementGen(ElementContainerImpl.java:170)
	at org.eclipse.e4.ui.model.application.ui.impl.ElementContainerImpl.setSelectedElement(ElementContainerImpl.java:188)
	at org.eclipse.e4.ui.internal.workbench.ModelServiceImpl.showElementInWindow(ModelServiceImpl.java:660)
	at org.eclipse.e4.ui.internal.workbench.ModelServiceImpl.bringToTop(ModelServiceImpl.java:624)
	at org.eclipse.e4.ui.internal.workbench.PartServiceImpl.delegateBringToTop(PartServiceImpl.java:786)
	at org.eclipse.e4.ui.internal.workbench.PartServiceImpl.bringToTop(PartServiceImpl.java:400)
	at org.eclipse.e4.ui.internal.workbench.PartServiceImpl.showPart(PartServiceImpl.java:1260)
	at org.eclipse.ui.internal.WorkbenchPage.busyOpenEditor(WorkbenchPage.java:3195)
	at org.eclipse.ui.internal.WorkbenchPage.lambda$9(WorkbenchPage.java:3100)
	at org.eclipse.swt.custom.BusyIndicator.showWhile(BusyIndicator.java:74)
	at org.eclipse.ui.internal.WorkbenchPage.openEditor(WorkbenchPage.java:3098)
	at org.eclipse.ui.internal.WorkbenchPage.openEditor(WorkbenchPage.java:3068)
	at org.eclipse.ui.internal.WorkbenchPage.openEditor(WorkbenchPage.java:3059)
	at org.eclipse.ui.ide.IDE.openEditor(IDE.java:569)
	at org.eclipse.ui.ide.IDE.openEditor(IDE.java:524)
	at org.eclipse.jdt.internal.ui.javaeditor.EditorUtility.openInEditor(EditorUtility.java:367)
	at org.eclipse.jdt.internal.ui.javaeditor.EditorUtility.openInEditor(EditorUtility.java:172)
	at org.eclipse.jdt.ui.actions.OpenAction.run(OpenAction.java:288)
	at org.eclipse.jdt.ui.actions.OpenAction.run(OpenAction.java:254)
	at org.eclipse.jdt.ui.actions.SelectionDispatchAction.dispatchRun(SelectionDispatchAction.java:274)
	at org.eclipse.jdt.ui.actions.SelectionDispatchAction.run(SelectionDispatchAction.java:252)
	at org.eclipse.jdt.internal.ui.navigator.OpenAndExpand.run(OpenAndExpand.java:53)
	at org.eclipse.ui.actions.RetargetAction.run(RetargetAction.java:215)
	at org.eclipse.ui.navigator.CommonNavigatorManager$1.open(CommonNavigatorManager.java:183)
	at org.eclipse.ui.OpenAndLinkWithEditorHelper$InternalListener.open(OpenAndLinkWithEditorHelper.java:48)
	at org.eclipse.jface.viewers.StructuredViewer$2.run(StructuredViewer.java:800)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:45)
	at org.eclipse.jface.util.SafeRunnable.run(SafeRunnable.java:174)
	at org.eclipse.jface.viewers.StructuredViewer.fireOpen(StructuredViewer.java:797)
	at org.eclipse.jface.viewers.StructuredViewer.handleOpen(StructuredViewer.java:1116)
	at org.eclipse.ui.navigator.CommonViewer.handleOpen(CommonViewer.java:454)
	at org.eclipse.jface.util.OpenStrategy.fireOpenEvent(OpenStrategy.java:275)
	at org.eclipse.jface.util.OpenStrategy$1.handleEvent(OpenStrategy.java:310)
	at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:89)
	at org.eclipse.swt.widgets.Display.sendEvent(Display.java:4237)
	at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1060)
	at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:4054)
	at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3626)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine$5.run(PartRenderingEngine.java:1150)
	at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:338)
	at org.eclipse.e4.ui.internal.workbench.swt.PartRenderingEngine.run(PartRenderingEngine.java:1041)
	at org.eclipse.e4.ui.internal.workbench.E4Workbench.createAndRunUI(E4Workbench.java:155)
	at org.eclipse.ui.internal.Workbench.lambda$3(Workbench.java:644)
	at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:338)
	at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:551)
	at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:156)
	at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:152)
	at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:203)
	at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:136)
	at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:104)
	at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:401)
	at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:255)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:566)
	at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:659)
	at org.eclipse.equinox.launcher.Main.basicRun(Main.java:596)
	at org.eclipse.equinox.launcher.Main.run(Main.java:1467)
	at org.eclipse.equinox.launcher.Main.main(Main.java:1440)

Start with the custom LabelProvider snippet and the stack trace at org.eclipse.xtext.ui.label.StylerFactory$DefaultFontStyler.applyStyles, then reproduce the issue by opening and closing the Outline View and running GC. Trace the created Font through StyledString rendering and determine whether it is disposed; done means the resource warning and any confirmed handle leak are addressed.