presto-accumulo/src/main/java/io/prestosql/plugin/accumulo/serializers/LexicoderRowSerializer.java/LexicoderRowSerializer/getMapLexicoder
class LexicoderRowSerializer:    private static MapLexicoder getMapLexicoder(Type type)
    {
        MapLexicoder<?, ?> mapLexicoder = MAP_LEXICODERS.get(type);
        if (mapLexicoder == null) {
            mapLexicoder = new MapLexicoder(
                    getLexicoder(Types.getKeyType(type)),
                    getLexicoder(Types.getValueType(type)));
            MAP_LEXICODERS.put(type, mapLexicoder);
        }
        return mapLexicoder;
    }