presto-main/src/main/java/io/prestosql/operator/NestedLoopJoinBridge.java/NestedLoopJoinBridge/whenBuildFinishes
class NestedLoopJoinBridge:    @Override
    default ListenableFuture<?> whenBuildFinishes()
    {
        return transform(getPagesFuture(), ignored -> null, directExecutor());
    }