presto-main/src/main/java/io/prestosql/operator/unnest/Unnester.java/Unnester/Unnester
class Unnester:    protected Unnester(Type... types)
    {
        requireNonNull(types, "types is null");
        this.unnestBlockBuilders = new UnnestBlockBuilder[types.length];
        this.currentPosition = 0;
        for (int i = 0; i < types.length; i++) {
            requireNonNull(types[i], "type is null");
            unnestBlockBuilders[i] = new UnnestBlockBuilder(types[i]);
        }
    }