Bug 45062 Don't filter output folder and class files
Create a Java project with source folder src and output folder bin. The bin folder will not be shown in the Packages Explorer. Create a Java project with source folder src and output folder output/bin. The output and bin folders are shown in the Packages Explorer. Implictly filtering out bin is confusing and inconsistent. A better way to do this would be to use a name filter for bin or add "Output folder" to the list of available filters.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/packageview/PackageExplorerPart.java
}
	protected void saveExpansionState(IMemento memento) {
		Object expandedElements[]= fViewer.getVisibleExpandedElements();
		if (expandedElements.length > 0) {
			IMemento expandedMem= memento.createChild(TAG_EXPANDED);
			for (int i= 0; i < expandedElements.length; i++) {
				IMemento elementMem= expandedMem.createChild(TAG_ELEMENT);
				
				Object o= expandedElements[i];
				if (o instanceof IJavaElement)
					elementMem.putString(TAG_PATH, ((IJavaElement) expandedElements[i]).getHandleIdentifier());
			}
		}
	}
	private void restoreFilterAndSorter() {
		fViewer.setSorter(new JavaElementSorter());
		if (fMemento != null)	
			fActionSet.restoreFilterAndSorterState(fMemento);
	}
	private void restoreUIState(IMemento memento) {
		restoreExpansionState(memento);
		restoreSelectionState(memento);
		
		
	}
	private void restoreLinkingEnabled(IMemento memento) {
		Integer val= memento.getInteger(PreferenceConstants.LINK_PACKAGES_TO_EDITOR);
		if (val != null) {
			fLinkingEnabled= val.intValue() != 0;
		}