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

        qualifierToNameMap.put(qualifier, name);
    }