@Override
        public Object get(final String fieldName) {
            return source.get(getPhysicalColumnName(modelName, fieldName));
        }
ElasticSearchConverter same as the HashMapConverter, but translate the column alias automatically.
oap-server/server-storage-plugin/storage-elasticsearch-plugin/src/main/java/org/apache/skywalking/oap/server/storage/plugin/elasticsearch/base/ElasticSearchConverter.java