src/vs/editor/common/services/textResourceConfigurationService.ts/TextResourceConfigurationService/_updateValue
class TextResourceConfigurationService:	private _updateValue(key: string, value: any, configurationTarget: ConfigurationTarget, overriddenValue: any | undefined, resource: URI, language: string | null): Promise<void> {
		if (language && overriddenValue !== undefined) {
			return this.configurationService.updateValue(key, value, { resource, overrideIdentifier: language }, configurationTarget);
		} else {
			return this.configurationService.updateValue(key, value, { resource }, configurationTarget);
		}
	}