• I have searched the issues of this repository and believe that this is not a duplicate.
• [] I have checked the FAQ of this repository and believe that this is not a duplicate.

Environment

• Dubbo version: master
• Operating System version: deepin 15.9
• Java version: 8

I want to know more about dubbo.And I found this code in module dubbo-metrics/dubbo-metrics-api/.../MetrcLevel

static {
        for (MetricLevel level : MetricLevel.values()) {
            if (level.ordinal() < 0) {
                throw new RuntimeException("MetricLevel can not < 0");
            }
        }
    }

I think this code is futility.Is it possible of level.ordinal() < 0?