src/vs/workbench/services/workingCopy/common/workingCopyHistoryService.ts/WorkingCopyHistoryModel/resolveEntriesOnce
class WorkingCopyHistoryModel:	private resolveEntriesOnce(): Promise<void> {
		if (!this.whenResolved) {
			this.whenResolved = this.doResolveEntries();
		}

		return this.whenResolved;
	}