address comments

Author: ConeyLiu

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/trees/TreeNodeSuite.scala

@@ -54,15 +54,15 @@ case class ComplexPlan(exprs: Seq[Seq[Expression]])
   override def output: Seq[Attribute] = Nil
 }
 
-case class ExpressionInMap(map: Map[String, Expression]) extends Expression with Unevaluable {
+case class ExpressionInMap(map: Map[String, Expression]) extends Unevaluable {
   override def children: Seq[Expression] = map.values.toSeq
   override def nullable: Boolean = true
   override def dataType: NullType = NullType
   override lazy val resolved = true
 }
 
 case class SeqTupleExpression(sons: Seq[(Expression, Expression)],
-    nonSons: Seq[(Expression, Expression)]) extends Expression with Unevaluable {
+    nonSons: Seq[(Expression, Expression)]) extends Unevaluable {
   override def children: Seq[Expression] = sons.flatMap(t => Iterator(t._1, t._2))
   override def nullable: Boolean = true
   override def dataType: NullType = NullType