@Override
    public final boolean combine(Metrics metrics) {
        LatestFunction latestFunction = (LatestFunction) metrics;
        this.value = latestFunction.value;
        return true;
    }
Service ID is required for sort query.
oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/analysis/meter/function/latest/LatestFunction.java