presto-main/src/main/java/io/prestosql/operator/aggregation/histogram/GroupedTypedHistogram.java/GroupedTypedHistogram/readAllValues
class GroupedTypedHistogram:    @Override
    public void readAllValues(HistogramValueReader reader)
    {
        iterateGroupNodes(currentGroupId, nodePointer -> {
            checkArgument(nodePointer != NULL, "should never see null here as we exclude in iterateGroupNodesCall");
            ValueNode valueNode = bucketNodeFactory.createValueNode(nodePointer);
            reader.read(values, valueNode.getValuePosition(), valueNode.getCount());
        });
    }