src/vs/workbench/browser/parts/activitybar/activitybarPart.ts/ActivitybarPart/setPlaceholderViewContainers
class ActivitybarPart:	private setPlaceholderViewContainers(placeholderViewContainers: IPlaceholderViewContainer[]): void {
		this.placeholderViewContainersValue = JSON.stringify(placeholderViewContainers);
	}