@Field
    public void setSizeFieldName(String sizeFieldName) {
        this.sizeFieldName = sizeFieldName;
    }
You can specify solrUrls, or you can specify solrZkHosts and use use zookeeper to determine the solr server urls.
tika-pipes/tika-pipes-iterators/tika-pipes-iterator-solr/src/main/java/org/apache/tika/pipes/pipesiterator/solr/SolrPipesIterator.java