presto-main/src/main/java/io/prestosql/operator/NestedLoopJoinPagesBuilder.java/NestedLoopJoinPagesBuilder/build
class NestedLoopJoinPagesBuilder:    public NestedLoopJoinPages build()
    {
        checkState(!finished, "NestedLoopJoinPagesBuilder is already finished");

        finished = true;
        pages = ImmutableList.copyOf(pages);
        return new NestedLoopJoinPages(pages, getEstimatedSize(), operatorContext);
    }