src/vs/platform/configuration/common/configurationModels.ts/Configuration/compareAndDeleteFolderConfiguration
class Configuration:	compareAndDeleteFolderConfiguration(folder: URI): IConfigurationChange {
		const folderConfig = this.folderConfigurations.get(folder);
		if (!folderConfig) {
			throw new Error('Unknown folder');
		}
		this.deleteFolderConfiguration(folder);
		const { added, updated, removed, overrides } = compare(folderConfig, undefined);
		return { keys: [...added, ...updated, ...removed], overrides };
	}