src/vs/workbench/contrib/callHierarchy/common/callHierarchy.ts/CallHierarchyModel/constructor
class CallHierarchyModel:	private constructor(
		readonly id: string,
		readonly provider: CallHierarchyProvider,
		readonly roots: CallHierarchyItem[],
		readonly ref: RefCountedDisposable,
	) {
		this.root = roots[0];
	}