private UntypedMetric get(Identifier dim, UntypedMetric other) {
        UntypedMetric v = values.get(dim);

        if (v == null) {
            v = new UntypedMetric(other.getMetricDefinition());
            values.put(dim, v);
        }
        return v;
    }
An aggregation of data which is only written to from a single thread.

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