presto-main/src/main/java/io/prestosql/operator/scalar/SplitToMultimapFunction.java/SplitToMultimapFunction/SplitToMultimapFunction
class SplitToMultimapFunction:    public SplitToMultimapFunction(@TypeParameter("map(varchar,array(varchar))") Type mapType)
    {
        pageBuilder = new PageBuilder(ImmutableList.of(mapType));
    }