default Optional<DocRef> fetchDefaultExtractionPipeline(DocRef docRef) {
        return Optional.empty();
    }
Get a default extraction pipeline if there is one.

@param docRef The document to get the default extraction pipeline for.
@return The default extraction pipeline.
stroom-query/stroom-query-api/src/main/java/stroom/query/api/datasource/DataSourceProvider.java