fix

Author: cloud-fan

sql/core/src/main/scala/org/apache/spark/sql/expressions/UserDefinedFunction.scala

@@ -139,7 +139,8 @@ case class UserDefinedFunction protected[sql] (
 object UserDefinedFunction {
   // This is to keep backward compatibility for this case class.
   // TODO: revisit this case class in Spark 3.0, and narrow down the public surface.
-  def unapply(arg: UserDefinedFunction): Option[(AnyRef, DataType, Option[Seq[DataType]])] = {
-    Some(arg.f, arg.dataType, arg.inputSchemas.map(_.map(_.dataType)))
+  def unapply(obj: Any): Option[(AnyRef, DataType, Option[Seq[DataType]])] = obj match {
+    case udf: UserDefinedFunction =>
+      Some((udf.f, udf.dataType, udf.inputSchemas.map(_.map(_.dataType))))
   }
 }