ESJava API-すべてのインデックス名を取得

/**
 *     index
 */
public static Set getAllIndices() {
    ActionFuture isr = client.admin().indices().stats(new IndicesStatsRequest().all());
    IndicesAdminClient indicesAdminClient = client.admin().indices();
    Map indexStatsMap = isr.actionGet().getIndices();
    Set set = isr.actionGet().getIndices().keySet();
    return set;
}