@Override
    public int hashCode() {
        return Objects.hash(
                super.hashCode(),
                description,
                maxDocsPerShard,
                partitionBy,
                partitionSize,
                shardsPerPartition,
                retentionDayAge,
                fields,
                timeField,
                volumeGroupName,
                defaultExtractionPipeline);
    }
@return A new builder for creating a {@link DocRef} for this document's type.
stroom-core-shared/src/main/java/stroom/index/shared/LuceneIndexDoc.java