void put(Number x) {
        outputFormat = AssumedType.GAUGE;
        current = x.doubleValue();
        if (histogram != null) {
            histogram.recordValue(current);
        }
        if (count > 0) {
            max = Math.max(current, max);
            min = Math.min(current, min);
            sum += current;
        } else {
            max = current;
            min = current;
            sum = current;
        }
        ++count;
    }
A gauge or a counter or... who knows? The class for storing a metric when the
metric has not been declared.

@author Steinar Knutsen
container-core/src/main/java/com/yahoo/metrics/simple/UntypedMetric.java