private void populateDimensionLessValue(String metricName, Bucket bucket, double x) {
        Identifier id = new Identifier(metricName, null);
        Sample wrappedX = new Sample(new Measurement(Double.valueOf(x)), id, AssumedType.GAUGE);
        bucket.put(wrappedX);
    }
Functional test for point persistence layer.

@author Steinar Knutsen
container-core/src/test/java/com/yahoo/metrics/simple/DimensionsCacheTest.java