Apply minor comments

sql/core/src/main/scala/org/apache/spark/sql/execution/aggregate/AggUtils.scala

@@ -83,8 +83,13 @@ object AggUtils {
     aggregateExpressions.map(e => e.copy(mode = updateMode(e.mode)))
   }
 
-  private[execution] def createPartialAggregate(operator: SparkPlan)
-      : (SparkPlan, SparkPlan) = operator match {
+  /**
+   * Builds new merge and map-side [[AggregateExec]]s from an input aggregate operator.
+   * If an aggregation needs a shuffle for satisfying its own distribution and supports partial
+   * aggregations, a map-side aggregation is appended before the shuffle in
+   * [[org.apache.spark.sql.execution.exchange.EnsureRequirements]].
+   */
+  def createMapMergeAggregatePair(operator: SparkPlan): (SparkPlan, SparkPlan) = operator match {
     case agg: AggregateExec =>
       val mapSideAgg = createPartialAggregateExec(
         agg.groupingExpressions, agg.aggregateExpressions, agg.child)

sql/core/src/main/scala/org/apache/spark/sql/execution/exchange/EnsureRequirements.scala

@@ -163,7 +163,7 @@ case class EnsureRequirements(conf: SQLConf) extends Rule[SparkPlan] {
       case PartialAggregate(childDist) if !operator.outputPartitioning.satisfies(childDist) =>
         // If an aggregation needs a shuffle and support partial aggregations, a map-side partial
         // aggregation and a shuffle are added as children.
-        val (mergeAgg, mapSideAgg) = AggUtils.createPartialAggregate(operator)
+        val (mergeAgg, mapSideAgg) = AggUtils.createMapMergeAggregatePair(operator)
         (mergeAgg, createShuffleExchange(requiredChildDistributions.head, mapSideAgg) :: Nil)
       case _ =>
         // Ensure that the operator's children satisfy their output distribution requirements: