Address comments.

Author: viirya

sql/core/src/main/scala/org/apache/spark/sql/execution/Expand.scala

@@ -93,7 +93,7 @@ case class Expand(
     child.asInstanceOf[CodegenSupport].produce(ctx, this)
   }
 
-  override def doConsume(ctx: CodegenContext, input: Seq[ExprCode], row: String = null): String = {
+  override def doConsume(ctx: CodegenContext, input: Seq[ExprCode], row: String): String = {
     /*
      * When the projections list looks like:
      *   expr1A, exprB, expr1C

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

@@ -135,7 +135,7 @@ case class TungstenAggregate(
     }
   }
 
-  override def doConsume(ctx: CodegenContext, input: Seq[ExprCode], row: String = null): String = {
+  override def doConsume(ctx: CodegenContext, input: Seq[ExprCode], row: String): String = {
     if (groupingExpressions.isEmpty) {
       doConsumeWithoutKeys(ctx, input)
     } else {

sql/core/src/main/scala/org/apache/spark/sql/execution/joins/BroadcastHashJoin.scala

@@ -107,7 +107,7 @@ case class BroadcastHashJoin(
     streamedPlan.asInstanceOf[CodegenSupport].produce(ctx, this)
   }
 
-  override def doConsume(ctx: CodegenContext, input: Seq[ExprCode], row: String = null): String = {
+  override def doConsume(ctx: CodegenContext, input: Seq[ExprCode], row: String): String = {
     if (joinType == Inner) {
       codegenInner(ctx, input)
     } else {