Bug 127105 Package explorer hierarchical mode calls ICompilationUnit#getChildren() in PackageExplorerProblemTreeViewer#isExpandable
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/packageview/PackageExplorerPart.java
protected Object[] getSortedChildren(Object parent) {
			IParentAwareSorter sorter= getSorter() instanceof IParentAwareSorter 
				? (IParentAwareSorter)getSorter()
				: null;
			if (sorter != null)
				sorter.setParent(parent);
			try {
				return super.getSortedChildren(parent);
			} finally {
				if (sorter != null)
					sorter.setParent(null);
			}
		}
		
	    
	    private boolean fInPreserveSelection;
		protected void preservingSelection(Runnable updateCode) {
			try {
				fInPreserveSelection= true;
				super.preservingSelection(updateCode);
			} finally {
				fInPreserveSelection= false;
			}
		}
		protected void setSelectionToWidget(ISelection selection, boolean reveal) {
			if (true) {
				super.setSelectionToWidget(selection, reveal);