src/vs/platform/log/common/log.ts/AbstractLoggerService/setLevel
class AbstractLoggerService:	setLevel(arg1: any, arg2?: any): void {
		const resource = URI.isUri(arg1) ? arg1 : undefined;
		const logLevel = resource ? arg2 : arg1;

		if (resource) {
			const logger = this.loggerItems.get(resource);
			if (logger && logger.logLevel !== logLevel) {
				logger.logLevel = logLevel;
				logger.logger.setLevel(logLevel);
			}
		} else {
			this.logLevel = logLevel;
			this.loggerItems.forEach(({ logLevel, logger }) => {
				if (logLevel === undefined) {
					logger.setLevel(this.logLevel);
				}
			});
		}

	}