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