apollo-core/src/main/java/com/ctrip/framework/apollo/core/utils/DeferredLogger.java/DeferredLogger/error
class DeferredLogger:  @Override
  public void error(String s, Throwable throwable) {
    if (isEnabled()) {
      DeferredLogCache.error(logger, s, throwable);
    } else {
      logger.error(s, throwable);
    }
  }