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