Address comments

Signed-off-by: Tomoyuki Morita <[email protected]>

Author: ykmr1224

common/src/main/java/org/opensearch/sql/common/utils/DebugUtils.java

@@ -9,7 +9,7 @@
 import java.util.Map;
 import java.util.stream.Collectors;
 
-/** Utility class for debugging operations. Should not be committed. */
+/** Utility class for debugging operations. */
 public class DebugUtils {
 
   private static void print(String format, Object... args) {

core/src/main/java/org/opensearch/sql/calcite/CalciteRelNodeVisitor.java

@@ -1898,10 +1898,9 @@ public RelNode visitRareTopN(RareTopN node, CalcitePlanContext context) {
 
     // 1. group the group-by list + field list and add a count() aggregation
     List<UnresolvedExpression> groupExprList = new ArrayList<>();
-    node.getGroupExprList().forEach(exp -> groupExprList.add(addAliasToDynamicFieldAccess(exp)));
+    node.getGroupExprList().forEach(exp -> groupExprList.add(addAliasToFieldAccess(exp)));
     // need alias for dynamic fields
-    node.getFields()
-        .forEach(field -> groupExprList.add(AstDSL.alias(field.getField().toString(), field)));
+    node.getFields().forEach(field -> groupExprList.add(addAliasToFieldAccess(field)));
     List<UnresolvedExpression> aggExprList =
         List.of(AstDSL.alias(countFieldName, AstDSL.aggregate("count", null)));
     aggregateWithTrimming(groupExprList, aggExprList, context);
@@ -2155,7 +2154,8 @@ public RelNode visitTimechart(
     }
   }
 
-  private UnresolvedExpression addAliasToDynamicFieldAccess(UnresolvedExpression exp) {
+  /** Add alias to Field. Needed for when the field is resolved as dynamic field access. */
+  private UnresolvedExpression addAliasToFieldAccess(UnresolvedExpression exp) {
     if (exp instanceof Field f) {
       return AstDSL.alias(f.getField().toString(), f);
     } else {

integ-test/src/test/java/org/opensearch/sql/calcite/standalone/CalciteDynamicFieldsAggregationIT.java

@@ -128,7 +128,7 @@ public void testEventstatsByDynamicField() throws IOException {
     String query =
         source(
             TEST_INDEX_DYNAMIC,
-            "eventstats count() as c by department" + "| fields id, city, department, c");
+            "eventstats count() as c by department | fields id, city, department, c");
 
     assertExplainYaml(
         query,