presto-accumulo/src/main/java/io/prestosql/plugin/accumulo/serializers/StringRowSerializer.java/StringRowSerializer/setMapping
class StringRowSerializer:    @Override
    public void setMapping(String name, String family, String qualifier)
    {
        columnValues.put(name, null);
        Map<String, String> qualifierColumnMap = familyQualifierColumnMap.get(family);
        if (qualifierColumnMap == null) {
            qualifierColumnMap = new HashMap<>();
            familyQualifierColumnMap.put(family, qualifierColumnMap);
        }

        qualifierColumnMap.put(qualifier, name);
    }