String catchAllTemplate() {
    return """
      {
        "index_patterns" : ["*"],
        "priority" : 5,
        "template": {
          "settings" : {
            "number_of_shards" : 1
          },
          "mappings" : {
            "_source": {"enabled": false }
          }
        }
      }\
      """;
  }
Catch-all template doesn't store source
zipkin-storage/elasticsearch/src/test/java/zipkin2/elasticsearch/integration/ITEnsureIndexTemplate.java