@Override
        public HistogramFunction storage2Entity(final Convert2Entity converter) {
            HistogramFunction metrics = new HistogramFunction() {
                @Override
                public AcceptableValue<BucketedValues> createNew() {
                    throw new UnexpectedException("createNew should not be called");
                }
            };
            metrics.setDataset(new DataTable((String) converter.get(DATASET)));
            metrics.setTimeBucket(((Number) converter.get(TIME_BUCKET)).longValue());
            metrics.setEntityId((String) converter.get(ENTITY_ID));
            return metrics;
        }
Histogram includes data range buckets and the amount matched/grouped in the buckets. This is for original histogram
graph visualization
oap-server/server-core/src/main/java/org/apache/skywalking/oap/server/core/analysis/meter/function/HistogramFunction.java