src/vs/workbench/contrib/codeEditor/browser/editorSettingsMigration.ts/EditorSettingsMigration/_migrateEditorSettingForFolderOverrideAndTarget
class EditorSettingsMigration:	private async _migrateEditorSettingForFolderOverrideAndTarget(migration: EditorSettingMigration, overrides: IConfigurationOverrides, data: IConfigurationValue<any>, dataKey: keyof IConfigurationValue<any>, target: ConfigurationTarget): Promise<void> {
		const value = data[dataKey];
		if (typeof value === 'undefined') {
			return;
		}

		const writeCalls: [string, any][] = [];
		const read: ISettingsReader = (key: string) => this._configurationService.inspect(`editor.${key}`, overrides)[dataKey];
		const write: ISettingsWriter = (key: string, value: any) => writeCalls.push([key, value]);
		migration.migrate(value, read, write);
		for (const [wKey, wValue] of writeCalls) {
			await this._configurationService.updateValue(`editor.${wKey}`, wValue, overrides, target);
		}
	}