[SPARK-19810][SPARK-19810][MINOR][FOLLOW-UP] Follow-ups from to remove Scala 2.10

## What changes were proposed in this pull request?

Follow up to a few comments on https://github.com/apache/spark/pull/17150#issuecomment-315020196 that couldn't be addressed before it was merged.

## How was this patch tested?

Existing tests.

Author: Sean Owen <sowen@cloudera.com>

Closes #18646 from srowen/SPARK-19810.2.

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/ScalaReflectionSuite.scala

@@ -17,17 +17,13 @@
 
 package org.apache.spark.sql.catalyst
 
-import java.net.URLClassLoader
 import java.sql.{Date, Timestamp}
 
-import scala.reflect.runtime.universe.typeOf
-
 import org.apache.spark.SparkFunSuite
 import org.apache.spark.sql.catalyst.expressions.{BoundReference, Literal, SpecificInternalRow}
 import org.apache.spark.sql.catalyst.expressions.objects.NewInstance
 import org.apache.spark.sql.types._
 import org.apache.spark.unsafe.types.UTF8String
-import org.apache.spark.util.Utils
 
 case class PrimitiveData(
     intField: Int,
@@ -339,39 +335,4 @@ class ScalaReflectionSuite extends SparkFunSuite {
     assert(linkedHashMapDeserializer.dataType == ObjectType(classOf[LHMap[_, _]]))
   }
 
-  private val dataTypeForComplexData = dataTypeFor[ComplexData]
-  private val typeOfComplexData = typeOf[ComplexData]
-
-  Seq(
-    ("mirror", () => mirror),
-    ("dataTypeFor", () => dataTypeFor[ComplexData]),
-    ("constructorFor", () => deserializerFor[ComplexData]),
-    ("extractorsFor", {
-      val inputObject = BoundReference(0, dataTypeForComplexData, nullable = false)
-      () => serializerFor[ComplexData](inputObject)
-    }),
-    ("getConstructorParameters(cls)", () => getConstructorParameters(classOf[ComplexData])),
-    ("getConstructorParameterNames", () => getConstructorParameterNames(classOf[ComplexData])),
-    ("getClassFromType", () => getClassFromType(typeOfComplexData)),
-    ("schemaFor", () => schemaFor[ComplexData]),
-    ("localTypeOf", () => localTypeOf[ComplexData]),
-    ("getClassNameFromType", () => getClassNameFromType(typeOfComplexData)),
-    ("getParameterTypes", () => getParameterTypes(() => ())),
-    ("getConstructorParameters(tpe)", () => getClassNameFromType(typeOfComplexData))).foreach {
-      case (name, exec) =>
-        test(s"SPARK-13640: thread safety of ${name}") {
-          (0 until 100).foreach { _ =>
-            val loader = new URLClassLoader(Array.empty, Utils.getContextOrSparkClassLoader)
-            (0 until 10).par.foreach { _ =>
-              val cl = Thread.currentThread.getContextClassLoader
-              try {
-                Thread.currentThread.setContextClassLoader(loader)
-                exec()
-              } finally {
-                Thread.currentThread.setContextClassLoader(cl)
-              }
-            }
-          }
-        }
-    }
 }

sql/core/src/main/scala/org/apache/spark/sql/execution/python/ExtractPythonUDFs.scala

@@ -133,7 +133,7 @@ object ExtractPythonUDFs extends Rule[SparkPlan] with PredicateHelper {
         val validUdfs = udfs.filter { udf =>
           // Check to make sure that the UDF can be evaluated with only the input of this child.
           udf.references.subsetOf(child.outputSet)
-        }.toArray
+        }
         if (validUdfs.nonEmpty) {
           val resultAttrs = udfs.zipWithIndex.map { case (u, i) =>
             AttributeReference(s"pythonUDF$i", u.dataType)()