RequestLogLevelMapper requestLogLevelMapper() {
        if (requestLogLevelMapper == null) {
            return DEFAULT_REQUEST_LOG_LEVEL_MAPPER;
        }
        return requestLogLevelMapper.orElse(DEFAULT_REQUEST_LOG_LEVEL_MAPPER);
    }
Sets the {@link RequestLogLevelMapper} to use when mapping the log level of request logs.
core/src/main/java/com/linecorp/armeria/common/logging/LogWriterBuilder.java