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