Address comments of abstraction

Author: Eric5553

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

@@ -24,11 +24,11 @@ import org.apache.spark.sql.execution.{ExplainUtils, UnaryExecNode}
 /**
  * Holds common logic for aggregate operators
  */
-abstract class BaseAggregateExec extends UnaryExecNode {
-  val groupingExpressions: Seq[NamedExpression]
-  val aggregateExpressions: Seq[AggregateExpression]
-  val aggregateAttributes: Seq[Attribute]
-  val resultExpressions: Seq[NamedExpression]
+trait BaseAggregateExec extends UnaryExecNode {
+  def groupingExpressions: Seq[NamedExpression]
+  def aggregateExpressions: Seq[AggregateExpression]
+  def aggregateAttributes: Seq[Attribute]
+  def resultExpressions: Seq[NamedExpression]
 
   override def verboseStringWithOperatorId(): String = {
     val inputString = child.output.mkString("[", ", ", "]")

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

@@ -47,11 +47,11 @@ import org.apache.spark.util.Utils
  */
 case class HashAggregateExec(
     requiredChildDistributionExpressions: Option[Seq[Expression]],
-    override val groupingExpressions: Seq[NamedExpression],
-    override val aggregateExpressions: Seq[AggregateExpression],
-    override val aggregateAttributes: Seq[Attribute],
+    groupingExpressions: Seq[NamedExpression],
+    aggregateExpressions: Seq[AggregateExpression],
+    aggregateAttributes: Seq[Attribute],
     initialInputBufferOffset: Int,
-    override val resultExpressions: Seq[NamedExpression],
+    resultExpressions: Seq[NamedExpression],
     child: SparkPlan)
   extends BaseAggregateExec with BlockingOperatorWithCodegen with AliasAwareOutputPartitioning {
 

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

@@ -61,11 +61,11 @@ import org.apache.spark.sql.execution.metric.SQLMetrics
  */
 case class ObjectHashAggregateExec(
     requiredChildDistributionExpressions: Option[Seq[Expression]],
-    override val groupingExpressions: Seq[NamedExpression],
-    override val aggregateExpressions: Seq[AggregateExpression],
-    override val aggregateAttributes: Seq[Attribute],
+    groupingExpressions: Seq[NamedExpression],
+    aggregateExpressions: Seq[AggregateExpression],
+    aggregateAttributes: Seq[Attribute],
     initialInputBufferOffset: Int,
-    override val resultExpressions: Seq[NamedExpression],
+    resultExpressions: Seq[NamedExpression],
     child: SparkPlan)
   extends BaseAggregateExec with AliasAwareOutputPartitioning {
 

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

@@ -32,11 +32,11 @@ import org.apache.spark.sql.execution.metric.SQLMetrics
  */
 case class SortAggregateExec(
     requiredChildDistributionExpressions: Option[Seq[Expression]],
-    override val groupingExpressions: Seq[NamedExpression],
-    override val aggregateExpressions: Seq[AggregateExpression],
-    override val aggregateAttributes: Seq[Attribute],
+    groupingExpressions: Seq[NamedExpression],
+    aggregateExpressions: Seq[AggregateExpression],
+    aggregateAttributes: Seq[Attribute],
     initialInputBufferOffset: Int,
-    override val resultExpressions: Seq[NamedExpression],
+    resultExpressions: Seq[NamedExpression],
     child: SparkPlan)
   extends BaseAggregateExec with AliasAwareOutputPartitioning {