for better code style

Author: AngersZhuuuu

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/optimizer/expressions.scala

@@ -374,8 +374,8 @@ object BooleanSimplification extends Rule[LogicalPlan] with PredicateHelper {
 
       case Not(Not(e)) => e
 
-      case Not(e: IsNull) => IsNotNull(e.child)
-      case Not(e: IsNotNull) => IsNull(e.child)
+      case Not(IsNull(e)) => IsNotNull(e)
+      case Not(IsNotNull(e)) => IsNull(e)
     }
   }
 }

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/optimizer/BooleanSimplificationSuite.scala

@@ -240,8 +240,8 @@ class BooleanSimplificationSuite extends PlanTest with ExpressionEvalHelper with
   }
 
   test("simplify NOT(IsNull(x)) and NOT(IsNotNull(x))") {
-    checkCondition(Not(IsNotNull(UnresolvedAttribute("b"))), IsNull(UnresolvedAttribute("b")))
-    checkCondition(Not(IsNull(UnresolvedAttribute("b"))), IsNotNull(UnresolvedAttribute("b")))
+    checkCondition(Not(IsNotNull('b)), IsNull('b))
+    checkCondition(Not(IsNull('b)), IsNotNull('b))
   }
 
   protected def assertEquivalent(e1: Expression, e2: Expression): Unit = {