public LogWriterBuilder requestLogLevelMapper(RequestLogLevelMapper requestLogLevelMapper) {
        requireNonNull(requestLogLevelMapper, "requestLogLevelMapper");
        if (this.requestLogLevelMapper == null) {
            this.requestLogLevelMapper = requestLogLevelMapper;
        } else {
            this.requestLogLevelMapper = this.requestLogLevelMapper.orElse(requestLogLevelMapper);
        }
        return this;
    }
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