presto-main/src/main/java/io/prestosql/operator/unnest/ReplicatedBlockBuilder.java/ReplicatedBlockBuilder/startNewOutput
class ReplicatedBlockBuilder:    public void startNewOutput(int expectedEntries)
    {
        checkState(source != null, "source is null");
        this.ids = new int[expectedEntries];
        this.positionCount = 0;
    }