@PipelineProperty(
            description = "Refresh the index after each batch is processed, making the indexed documents visible to " +
                          "searches.",
            defaultValue = "false",
            displayPriority = 3
    )
    public void setRefreshAfterEachBatch(final boolean refreshAfterEachBatch) {
        this.refreshAfterEachBatch = refreshAfterEachBatch;
    }
Build the index name, substituting values from the source document where specified.
For instance, consider an index name of `stroom-index-{_year}`. A field `<string key='_year'>2023</string>` in
the doc root will result in a destination index of `stroom-index-2023` for that document. In this case, because
the field `_year` starts with an underscore, it is not rendered to the doc and instead is solely used in the
index name.
stroom-search/stroom-search-elastic/src/main/java/stroom/search/elastic/indexing/ElasticIndexingFilter.java