diff --git a/sql/catalyst/src/main/scala-2.13/org/apache/spark/sql/catalyst/expressions/ExpressionSet.scala b/sql/catalyst/src/main/scala-2.13/org/apache/spark/sql/catalyst/expressions/ExpressionSet.scala
deleted file mode 100644
index 0d4b401ea2eb..000000000000
--- a/sql/catalyst/src/main/scala-2.13/org/apache/spark/sql/catalyst/expressions/ExpressionSet.scala
+++ /dev/null
@@ -1,106 +0,0 @@
-/*
- * Licensed to the Apache Software Foundation (ASF) under one or more
- * contributor license agreements.  See the NOTICE file distributed with
- * this work for additional information regarding copyright ownership.
- * The ASF licenses this file to You under the Apache License, Version 2.0
- * (the "License"); you may not use this file except in compliance with
- * the License.  You may obtain a copy of the License at
- *
- *    http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.apache.spark.sql.catalyst.expressions
-
-import scala.collection.{mutable, View}
-import scala.collection.mutable.ArrayBuffer
-
-object ExpressionSet {
-  /** Constructs a new [[ExpressionSet]] by applying [[Canonicalize]] to `expressions`. */
-  def apply(expressions: TraversableOnce[Expression]): ExpressionSet = {
-    val set = new ExpressionSet()
-    expressions.foreach(set.add)
-    set
-  }
-}
-
-/**
- * A [[Set]] where membership is determined based on determinacy and a canonical representation of
- * an [[Expression]] (i.e. one that attempts to ignore cosmetic differences).
- * See [[Canonicalize]] for more details.
- *
- * Internally this set uses the canonical representation, but keeps also track of the original
- * expressions to ease debugging.  Since different expressions can share the same canonical
- * representation, this means that operations that extract expressions from this set are only
- * guaranteed to see at least one such expression.  For example:
- *
- * {{{
- *   val set = ExpressionSet(a + 1, 1 + a)
- *
- *   set.iterator => Iterator(a + 1)
- *   set.contains(a + 1) => true
- *   set.contains(1 + a) => true
- *   set.contains(a + 2) => false
- * }}}
- *
- * For non-deterministic expressions, they are always considered as not contained in the [[Set]].
- * On adding a non-deterministic expression, simply append it to the original expressions.
- * This is consistent with how we define `semanticEquals` between two expressions.
- */
-class ExpressionSet protected(
-    protected val baseSet: mutable.Set[Expression] = new mutable.HashSet,
-    protected val originals: mutable.Buffer[Expression] = new ArrayBuffer)
-  extends Set[Expression] {
-
-  //  Note: this class supports Scala 2.13. A parallel source tree has a 2.12 implementation.
-
-  protected def add(e: Expression): Unit = {
-    if (!e.deterministic) {
-      originals += e
-    } else if (!baseSet.contains(e.canonicalized) ) {
-      baseSet.add(e.canonicalized)
-      originals += e
-    }
-  }
-
-  override def contains(elem: Expression): Boolean = baseSet.contains(elem.canonicalized)
-
-  override def incl(elem: Expression): ExpressionSet = {
-    val newSet = new ExpressionSet(baseSet.clone(), originals.clone())
-    newSet.add(elem)
-    newSet
-  }
-
-  override def excl(elem: Expression): ExpressionSet = {
-    if (elem.deterministic) {
-      val newBaseSet = baseSet.clone().filterNot(_ == elem.canonicalized)
-      val newOriginals = originals.clone().filterNot(_.canonicalized == elem.canonicalized)
-      new ExpressionSet(newBaseSet, newOriginals)
-    } else {
-      new ExpressionSet(baseSet.clone(), originals.clone())
-    }
-  }
-
-  override def concat(elems: IterableOnce[Expression]): Set[Expression] = {
-    val newSet = new ExpressionSet(baseSet.clone(), originals.clone())
-    elems.iterator.foreach(newSet.add)
-    newSet
-  }
-
-  override def iterator: Iterator[Expression] = originals.iterator
-
-  /**
-   * Returns a string containing both the post [[Canonicalize]] expressions and the original
-   * expressions in this set.
-   */
-  def toDebugString: String =
-    s"""
-       |baseSet: ${baseSet.mkString(", ")}
-       |originals: ${originals.mkString(", ")}
-     """.stripMargin
-}
diff --git a/sql/catalyst/src/main/scala-2.12/org/apache/spark/sql/catalyst/expressions/ExpressionSet.scala b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/ExpressionSet.scala
similarity index 100%
rename from sql/catalyst/src/main/scala-2.12/org/apache/spark/sql/catalyst/expressions/ExpressionSet.scala
rename to sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/ExpressionSet.scala