presto-orc/src/main/java/io/prestosql/orc/OrcWriter.java/OrcWriter/getRetainedBytes
class OrcWriter:    public long getRetainedBytes()
    {
        return INSTANCE_SIZE +
                columnWritersRetainedBytes +
                closedStripesRetainedBytes +
                orcDataSink.getRetainedSizeInBytes() +
                (validationBuilder == null ? 0 : validationBuilder.getRetainedSize());
    }