diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/joins/BroadcastHashOuterJoin.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/joins/BroadcastHashOuterJoin.scala
index 372cd22d80e27..0b01027e6fc47 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/joins/BroadcastHashOuterJoin.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/joins/BroadcastHashOuterJoin.scala
@@ -20,7 +20,7 @@ package org.apache.spark.sql.execution.joins
 import org.apache.spark.annotation.DeveloperApi
 import org.apache.spark.rdd.RDD
 import org.apache.spark.sql.catalyst.expressions._
-import org.apache.spark.sql.catalyst.plans.physical.UnspecifiedDistribution
+import org.apache.spark.sql.catalyst.plans.physical.{Distribution, UnspecifiedDistribution}
 import org.apache.spark.sql.catalyst.plans.{JoinType, LeftOuter, RightOuter}
 import org.apache.spark.sql.execution.{BinaryNode, SparkPlan}
 import org.apache.spark.util.ThreadUtils
@@ -53,7 +53,7 @@ case class BroadcastHashOuterJoin(
     }
   }
 
-  override def requiredChildDistribution =
+  override def requiredChildDistribution: Seq[Distribution] =
     UnspecifiedDistribution :: UnspecifiedDistribution :: Nil
 
   private[this] lazy val (buildPlan, streamedPlan) = joinType match {
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/joins/ShuffledHashOuterJoin.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/joins/ShuffledHashOuterJoin.scala
index 670666ca0512f..cfc9c14aaa363 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/joins/ShuffledHashOuterJoin.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/joins/ShuffledHashOuterJoin.scala
@@ -20,7 +20,7 @@ package org.apache.spark.sql.execution.joins
 import org.apache.spark.annotation.DeveloperApi
 import org.apache.spark.rdd.RDD
 import org.apache.spark.sql.catalyst.expressions._
-import org.apache.spark.sql.catalyst.plans.physical.ClusteredDistribution
+import org.apache.spark.sql.catalyst.plans.physical.{Distribution, ClusteredDistribution}
 import org.apache.spark.sql.catalyst.plans.{FullOuter, JoinType, LeftOuter, RightOuter}
 import org.apache.spark.sql.execution.{BinaryNode, SparkPlan}
 
@@ -40,7 +40,7 @@ case class ShuffledHashOuterJoin(
     left: SparkPlan,
     right: SparkPlan) extends BinaryNode with HashOuterJoin {
 
-  override def requiredChildDistribution: Seq[ClusteredDistribution] =
+  override def requiredChildDistribution: Seq[Distribution] =
     ClusteredDistribution(leftKeys) :: ClusteredDistribution(rightKeys) :: Nil
 
   protected override def doExecute(): RDD[InternalRow] = {
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/JoinSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/JoinSuite.scala
index 090c05f87ca61..8953889d1fae9 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/JoinSuite.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/JoinSuite.scala
@@ -87,7 +87,8 @@ class JoinSuite extends QueryTest with BeforeAndAfterEach {
         classOf[ShuffledHashOuterJoin]),
       ("SELECT * FROM testData right join testData2 ON key = a and key = 2",
         classOf[ShuffledHashOuterJoin]),
-      ("SELECT * FROM testData full outer join testData2 ON key = a", classOf[ShuffledHashOuterJoin]),
+      ("SELECT * FROM testData full outer join testData2 ON key = a",
+        classOf[ShuffledHashOuterJoin]),
       ("SELECT * FROM testData left JOIN testData2 ON (key * a != key + a)",
         classOf[BroadcastNestedLoopJoin]),
       ("SELECT * FROM testData right JOIN testData2 ON (key * a != key + a)",
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/SparkPlanTest.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/SparkPlanTest.scala
index 2de83109e40a6..108b1122f7bff 100644
--- a/sql/core/src/test/scala/org/apache/spark/sql/execution/SparkPlanTest.scala
+++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/SparkPlanTest.scala
@@ -99,9 +99,9 @@ class SparkPlanTest extends SparkFunSuite {
    * @param expectedAnswer the expected result in a [[Seq]] of [[Product]]s.
    */
   protected def checkAnswer[A <: Product : TypeTag](
-    input: DataFrame,
-    planFunction: SparkPlan => SparkPlan,
-    expectedAnswer: Seq[A]): Unit = {
+      input: DataFrame,
+      planFunction: SparkPlan => SparkPlan,
+      expectedAnswer: Seq[A]): Unit = {
     val expectedRows = expectedAnswer.map(Row.fromTuple)
     checkAnswer(input, planFunction, expectedRows)
   }
@@ -115,10 +115,10 @@ class SparkPlanTest extends SparkFunSuite {
    * @param expectedAnswer the expected result in a [[Seq]] of [[Product]]s.
    */
   protected def checkAnswer[A <: Product : TypeTag](
-    left: DataFrame,
-    right: DataFrame,
-    planFunction: (SparkPlan, SparkPlan) => SparkPlan,
-    expectedAnswer: Seq[A]): Unit = {
+      left: DataFrame,
+      right: DataFrame,
+      planFunction: (SparkPlan, SparkPlan) => SparkPlan,
+      expectedAnswer: Seq[A]): Unit = {
     val expectedRows = expectedAnswer.map(Row.fromTuple)
     checkAnswer(left, right, planFunction, expectedRows)
   }