[jvm-packages] fix the prediction issue for multi:softmax (#7694)

jvm-packages/xgboost4j-spark/src/test/scala/ml/dmlc/xgboost4j/scala/spark/XGBoostClassifierSuite.scala

@@ -1,5 +1,5 @@
 /*
- Copyright (c) 2014 by Contributors
+ Copyright (c) 2014-2022 by Contributors
 
  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
@@ -17,9 +17,11 @@
 package ml.dmlc.xgboost4j.scala.spark
 
 import ml.dmlc.xgboost4j.scala.{DMatrix, XGBoost => ScalaXGBoost}
+
 import org.apache.spark.ml.linalg._
 import org.apache.spark.sql._
 import org.scalatest.FunSuite
+
 import org.apache.spark.Partitioner
 
 class XGBoostClassifierSuite extends FunSuite with PerTest {
@@ -102,6 +104,8 @@ class XGBoostClassifierSuite extends FunSuite with PerTest {
     assert(model.getEta == 0.1)
     assert(model.getMaxDepth == 6)
     assert(model.numClasses == 6)
+    val transformedDf = model.transform(trainingDF)
+    assert(!transformedDf.columns.contains("probability"))
   }
 
   test("use base margin") {