@Override
    public String toString() {
        return "ElasticIndex{" +
               "description='" + description + '\'' +
               ", clusterRef='" + clusterRef + '\'' +
               ", indexName='" + indexName + '\'' +
               ", searchSlices=" + searchSlices +
               ", searchScrollSize=" + searchScrollSize +
               ", fields=" + fields +
               ", timeField=" + timeField +
               ", defaultExtractionPipeline=" + defaultExtractionPipeline +
               '}';
    }
@return A new builder for creating a {@link DocRef} for this document's type.
stroom-core-shared/src/main/java/stroom/search/elastic/shared/ElasticIndexDoc.java