Address coderrabbit comments

Signed-off-by: Srikanth Padakanti <srikanth_padakanti@apple.com>

Author: srikanthpadakanti

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

@@ -3118,122 +3118,6 @@ public RelNode visitExpand(Expand expand, CalcitePlanContext context) {
     return context.relBuilder.peek();
   }
 
-  //    /**
-  //     * mvcombine command visitor to collapse rows that are identical on all fields except the
-  // target
-  //     * field, and combine the target field values into a multivalue (array) field.
-  //     *
-  //     *
-  //     * @param node mvcombine command to be visited
-  //     * @param context CalcitePlanContext containing the RelBuilder, RexBuilder, and resolution
-  // context
-  //     * @return RelNode representing records collapsed by all non-target fields with the target
-  // field
-  //     *     combined into a multivalue array (or a delimited string when {@code nomv=true})
-  //     */
-  //  @Override
-  //  public RelNode visitMvCombine(MvCombine node, CalcitePlanContext context) {
-  //    // 1) Lower child first
-  //    visitChildren(node, context);
-  //
-  //    final RelBuilder relBuilder = context.relBuilder;
-  //    final RexBuilder rexBuilder = context.rexBuilder;
-  //
-  //    final RelNode input = relBuilder.peek();
-  //    final List<String> inputFieldNames = input.getRowType().getFieldNames();
-  //
-  //    // 2) Accept delim (default is single space).
-  //    // NOTE: delim only affects single-value rendering when nomv=true.
-  //    final String delim = node.getDelim();
-  //
-  //    // 3) Resolve target field to an input ref (must be a direct field reference)
-  //    final Field targetField = node.getField();
-  //    final RexNode targetRex = rexVisitor.analyze(targetField, context);
-  //    if (!(targetRex instanceof RexInputRef)) {
-  //      throw new SemanticCheckException(
-  //          "mvcombine target must be a direct field reference, but got: " + targetField);
-  //    }
-  //    final int targetIndex = ((RexInputRef) targetRex).getIndex();
-  //    final String targetName = inputFieldNames.get(targetIndex);
-  //
-  //    // 4) Group key = all fields except target
-  //    final List<RexNode> groupExprs = new ArrayList<>();
-  //    for (int i = 0; i < inputFieldNames.size(); i++) {
-  //      if (i == targetIndex) continue;
-  //      groupExprs.add(relBuilder.field(i));
-  //    }
-  //
-  //    // 5) Aggregate target values: COLLECT => MULTISET
-  //    final RelBuilder.AggCall aggCall =
-  //        relBuilder
-  //            .aggregateCall(SqlStdOperatorTable.COLLECT, relBuilder.field(targetIndex))
-  //            .as(targetName);
-  //
-  //    relBuilder.aggregate(relBuilder.groupKey(groupExprs), aggCall);
-  //
-  //    // 6) Restore original output column order AND cast MULTISET -> ARRAY using RexBuilder
-  //    // After aggregate => [group fields..., targetAgg(multiset)]
-  //    final int aggPos = groupExprs.size();
-  //
-  //    final RelDataType elemType = input.getRowType().getFieldList().get(targetIndex).getType();
-  //    final RelDataType arrayType = relBuilder.getTypeFactory().createArrayType(elemType, -1);
-  //
-  //    final List<RexNode> projections = new ArrayList<>(inputFieldNames.size());
-  //    final List<String> projNames = new ArrayList<>(inputFieldNames.size());
-  //
-  //    int groupPos = 0;
-  //    for (int i = 0; i < inputFieldNames.size(); i++) {
-  //      projNames.add(inputFieldNames.get(i));
-  //      if (i == targetIndex) {
-  //        final RexNode multisetRef = relBuilder.field(aggPos); // MULTISET
-  //        projections.add(rexBuilder.makeCast(arrayType, multisetRef)); // ARRAY
-  //      } else {
-  //        projections.add(relBuilder.field(groupPos));
-  //        groupPos++;
-  //      }
-  //    }
-  //    relBuilder.project(projections, projNames, /* force= */ true);
-  //
-  //    // 7) nomv=true converts multivalue output to a single delimited string.
-  //    // arrayToString in this engine supports only String/ByteString, so cast elements to STRING
-  //    // first.
-  //    if (node.isNomv()) {
-  //      final List<RexNode> nomvProjections = new ArrayList<>(inputFieldNames.size());
-  //      final List<String> nomvNames = new ArrayList<>(inputFieldNames.size());
-  //
-  //      // Build ARRAY<VARCHAR> type once
-  //      final RelDataType stringType =
-  //          relBuilder
-  //              .getTypeFactory()
-  //              .createSqlType(org.apache.calcite.sql.type.SqlTypeName.VARCHAR);
-  //      final RelDataType stringArrayType =
-  //          relBuilder.getTypeFactory().createArrayType(stringType, -1);
-  //
-  //      for (int i = 0; i < inputFieldNames.size(); i++) {
-  //        final String name = inputFieldNames.get(i);
-  //        nomvNames.add(name);
-  //
-  //        if (i == targetIndex) {
-  //          // At this point relBuilder.field(i) is ARRAY<elemType>. Cast to ARRAY<VARCHAR> so
-  //          // ARRAY_TO_STRING works.
-  //          final RexNode stringArray = rexBuilder.makeCast(stringArrayType, relBuilder.field(i));
-  //
-  //          nomvProjections.add(
-  //              relBuilder.call(
-  //                  org.apache.calcite.sql.fun.SqlLibraryOperators.ARRAY_TO_STRING,
-  //                  stringArray,
-  //                  relBuilder.literal(delim)));
-  //        } else {
-  //          nomvProjections.add(relBuilder.field(i));
-  //        }
-  //      }
-  //
-  //      relBuilder.project(nomvProjections, nomvNames, /* force= */ true);
-  //    }
-  //
-  //    return relBuilder.peek();
-  //  }
-
   /**
    * mvcombine command visitor to collapse rows that are identical on all fields except the target
    * field, and combine the target field values into a multivalue (array) field.