Bug 41491 Add constructors from fields issues
200300813 a. add visibility buttons like 'Add constructor from super class'
org.eclipse.jdt.ui/ui/org/eclipse/jdt/ui/actions/GenerateNewConstructorUsingFieldsAction.java
private List fFieldsList;
		private static final Object[] EMPTY= new Object[0];
		public GenerateConstructorUsingFieldsContentProvider(List fieldList) {
			fFieldsList= fieldList;
		}
		/*
		 * @see ITreeContentProvider#getChildren(Object)
		 */
		public Object[] getChildren(Object parentElement) {
			return EMPTY;
		}
		/*
		 * @see ITreeContentProvider#getParent(Object)
		 */
		public Object getParent(Object element) {
			return null;
		}
		/*
		 * @see ITreeContentProvider#hasChildren(Object)
		 */
		public boolean hasChildren(Object element) {
			return getChildren(element).length > 0;