presto-raptor-legacy/src/main/java/io/prestosql/plugin/raptor/legacy/systemtables/PageListBuilder.java/PageListBuilder/build
class PageListBuilder:    public List<Page> build()
    {
        if (!pageBuilder.isEmpty()) {
            pages.add(pageBuilder.build());
            pageBuilder.reset();
        }
        return pages.build();
    }