adding startreenode related tests

Signed-off-by: Bharathwaj G <[email protected]>

Author: bharath-techie

server/src/main/java/org/opensearch/index/codec/composite/Composite99DocValuesWriter.java

@@ -195,7 +195,8 @@ private void mergeStarTreeFields(MergeState mergeState) throws IOException {
                 }
             }
         }
-        final StarTreesBuilder starTreesBuilder = new StarTreesBuilder(state, mapperService);
-        starTreesBuilder.buildDuringMerge(starTreeSubsPerField);
+        try (StarTreesBuilder starTreesBuilder = new StarTreesBuilder(state, mapperService)) {
+            starTreesBuilder.buildDuringMerge(starTreeSubsPerField);
+        }
     }
 }

server/src/main/java/org/opensearch/index/compositeindex/datacube/startree/builder/BaseStarTreeBuilder.java

@@ -120,7 +120,7 @@ protected BaseStarTreeBuilder(StarTreeField starTreeField, SegmentWriteState sta
     public List<MetricAggregatorInfo> generateMetricAggregatorInfos(MapperService mapperService) {
         List<MetricAggregatorInfo> metricAggregatorInfos = new ArrayList<>();
         for (Metric metric : this.starTreeField.getMetrics()) {
-            for (MetricStat metricType : metric.getMetrics()) {
+            for (MetricStat metricStat : metric.getMetrics()) {
                 IndexNumericFieldData.NumericType numericType;
                 Mapper fieldMapper = mapperService.documentMapper().mappers().getMapper(metric.getField());
                 if (fieldMapper instanceof NumberFieldMapper) {
@@ -131,7 +131,7 @@ public List<MetricAggregatorInfo> generateMetricAggregatorInfos(MapperService ma
                 }
 
                 MetricAggregatorInfo metricAggregatorInfo = new MetricAggregatorInfo(
-                    metricType,
+                    metricStat,
                     metric.getField(),
                     starTreeField.getName(),
                     numericType
@@ -457,13 +457,13 @@ public List<SequentialDocValuesIterator> getMetricReaders(SegmentWriteState stat
         throws IOException {
         List<SequentialDocValuesIterator> metricReaders = new ArrayList<>();
         for (Metric metric : this.starTreeField.getMetrics()) {
-            for (MetricStat metricType : metric.getMetrics()) {
+            for (MetricStat metricStat : metric.getMetrics()) {
                 FieldInfo metricFieldInfo = state.fieldInfos.fieldInfo(metric.getField());
                 if (metricFieldInfo == null) {
                     metricFieldInfo = getFieldInfo(metric.getField());
                 }
                 // TODO
-                // if (metricType != MetricStat.COUNT) {
+                // if (metricStat != MetricStat.COUNT) {
                 // Need not initialize the metric reader for COUNT metric type
                 SequentialDocValuesIterator metricReader = new SequentialDocValuesIterator(
                     fieldProducerMap.get(metricFieldInfo.name).getSortedNumeric(metricFieldInfo)
@@ -516,6 +516,10 @@ void build(Iterator<StarTreeDocument> starTreeDocumentIterator) throws IOExcepti
 
     }
 
+    TreeNode getRootNode() {
+        return rootNode;
+    }
+
     /**
      * Adds a document to star-tree
      *