Github user nickwallen commented on a diff in the pull request:
https://github.com/apache/metron/pull/832#discussion_r149182580
--- Diff:
metron-platform/metron-elasticsearch/src/main/java/org/apache/metron/elasticsearch/dao/ElasticsearchColumnMetadataDao.java
---
@@ -0,0 +1,192 @@
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.metron.elasticsearch.dao;
+
+import org.apache.metron.elasticsearch.utils.ElasticsearchUtils;
+import org.apache.metron.indexing.dao.search.FieldType;
+import
org.elasticsearch.action.admin.indices.mapping.get.GetMappingsRequest;
+import org.elasticsearch.client.AdminClient;
+import org.elasticsearch.cluster.metadata.MappingMetaData;
+import org.elasticsearch.common.collect.ImmutableOpenMap;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.IOException;
+import java.lang.invoke.MethodHandles;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+
+import static
org.apache.metron.elasticsearch.utils.ElasticsearchUtils.INDEX_NAME_DELIMITER;
+
+/**
+ * Responsible for retrieving column-level metadata for Elasticsearch
search indices.
+ */
+public class ElasticsearchColumnMetadataDao implements ColumnMetadataDao {
--- End diff --
Extracting this logic into its own implementation class made it possible
for me to test the new sort logic. Just using mocks was not possible due to
some of the key methods in the Elasticsearch API being declared final.
---
