Bug 27764 IResource.findMarkers is called too often
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/packageview/PackageExplorerActionGroup.java
import org.eclipse.jdt.core.ICompilationUnit;
import org.eclipse.jdt.core.IJavaElement;
import org.eclipse.jdt.core.IOpenable;
import org.eclipse.jdt.ui.IContextMenuConstants;
import org.eclipse.jdt.ui.JavaUI;
import org.eclipse.jdt.ui.PreferenceConstants;
import org.eclipse.jdt.ui.actions.BuildActionGroup;
import org.eclipse.jdt.ui.actions.CCPActionGroup;
import org.eclipse.jdt.ui.actions.CustomFiltersActionGroup;
import org.eclipse.jdt.ui.actions.GenerateActionGroup;
import org.eclipse.jdt.ui.actions.ImportActionGroup;
import org.eclipse.jdt.ui.actions.JavaSearchActionGroup;
import org.eclipse.jdt.ui.actions.JdtActionConstants;
import org.eclipse.jdt.ui.actions.MemberFilterActionGroup;
import org.eclipse.jdt.ui.actions.NavigateActionGroup;
import org.eclipse.jdt.ui.actions.ProjectActionGroup;
import org.eclipse.jdt.ui.actions.RefactorActionGroup;
import org.eclipse.jdt.ui.actions.ShowActionGroup;
import org.eclipse.jdt.internal.ui.actions.CompositeActionGroup;
import org.eclipse.jdt.internal.ui.actions.NewWizardsActionGroup;
import org.eclipse.jdt.internal.ui.workingsets.WorkingSetFilterActionGroup;
class PackageExplorerActionGroup extends CompositeActionGroup implements ISelectionChangedListener {
	private PackageExplorerPart fPart;
	private GoIntoAction fZoomInAction;
 	private BackAction fBackAction;
	private ForwardAction fForwardAction;
	private UpAction fUpAction;
	private GotoTypeAction fGotoTypeAction;
	private GotoPackageAction fGotoPackageAction;
	private GotoResourceAction fGotoResourceAction;