if (treeAction != null) {
items.add(new ActionContributionItem(treeAction));
}
if (categoryProvider != null) {
items.add(new ActionContributionItem(
new GroupByAction(categoryProvider, groupByActions
.toArray(new IAction[0]))));
}
if (visualProviders != null) {
items.add(new ActionContributionItem(
new ColorByAction(colorByActions.toArray(new IAction[0]))));