presto-main/src/main/java/io/prestosql/operator/SpatialIndexBuilderOperator.java/SpatialIndexBuilderOperator/isFinished
class SpatialIndexBuilderOperator:    @Override
    public boolean isFinished()
    {
        if (finished) {
            return true;
        }

        if (finishing && indexNotNeeded.isDone()) {
            index.clear();
            localUserMemoryContext.setBytes(index.getEstimatedSize().toBytes());
            finished = true;
        }

        return finished;
    }