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