static int stringToLevel(String levelStr) {
        if ("trace".equalsIgnoreCase(levelStr)) {
            return SimpleLogger.LOG_LEVEL_TRACE;
        } else if ("debug".equalsIgnoreCase(levelStr)) {
            return SimpleLogger.LOG_LEVEL_DEBUG;
        } else if ("info".equalsIgnoreCase(levelStr)) {
            return SimpleLogger.LOG_LEVEL_INFO;
        } else if ("warn".equalsIgnoreCase(levelStr)) {
            return SimpleLogger.LOG_LEVEL_WARN;
        } else if ("error".equalsIgnoreCase(levelStr)) {
            return SimpleLogger.LOG_LEVEL_ERROR;
        } else if ("off".equalsIgnoreCase(levelStr)) {
            return SimpleLogger.LOG_LEVEL_OFF;
        }
        // assume INFO by default
        return SimpleLogger.LOG_LEVEL_INFO;
    }
See https://jira.qos.ch/browse/SLF4J-499
@since 1.7.33 and 2.0.0-alpha6
slf4j-simple/src/main/java/org/slf4j/simple/SimpleLoggerConfiguration.java