presto-main/src/main/java/io/prestosql/operator/exchange/PageChannelSelector.java/PageChannelSelector/PageChannelSelector
class PageChannelSelector:    public PageChannelSelector(int... channels)
    {
        checkArgument(IntStream.of(channels).allMatch(channel -> channel >= 0), "channels must be positive");
        this.channels = requireNonNull(channels, "channels is null").clone();
    }