presto-iceberg/src/main/java/io/prestosql/plugin/iceberg/IcebergPageSink.java/IcebergPageSink/appendPage
class IcebergPageSink:    @Override
    public CompletableFuture<?> appendPage(Page page)
    {
        hdfsEnvironment.doAs(session.getUser(), () -> doAppend(page));

        return NOT_BLOCKED;
    }