public static Layer valueOf(int value) {
        Layer layer = DICTIONARY.get(value);
        if (layer == null) {
            throw new UnexpectedException("Unknown Layer value");
        }
        return layer;
    }
The `normal` status represents this service is detected by an agent. The `un-normal` service is conjectured by
telemetry data collected from agents on/in the `normal` service.
oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/analysis/Layer.java