## What changes were proposed in this pull request?
Currently, running the codes in Java
```java
spark.udf().register("inc", new UDF1<Long, Long>() {
Override
public Long call(Long i) {
return i + 1;
}
}, DataTypes.LongType);
spark.range(10).toDF("x").createOrReplaceTempView("tmp");
Row result = spark.sql("SELECT inc(x) FROM tmp GROUP BY inc(x)").head();
Assert.assertEquals(7, result.getLong(0));
```
fails as below:
```
org.apache.spark.sql.AnalysisException: expression 'tmp.`x`' is neither present in the group by, nor is it an aggregate function. Add to group by or wrap in first() (or first_value) if you don't care which value you get.;;
Aggregate [UDF(x#19L)], [UDF(x#19L) AS UDF(x)#23L]
+- SubqueryAlias tmp, `tmp`
+- Project [id#16L AS x#19L]
+- Range (0, 10, step=1, splits=Some(8))
at org.apache.spark.sql.catalyst.analysis.CheckAnalysis$class.failAnalysis(CheckAnalysis.scala:40)
at org.apache.spark.sql.catalyst.analysis.Analyzer.failAnalysis(Analyzer.scala:57)
```
The root cause is because we were creating the function every time when it needs to build as below:
```scala
scala> def inc(i: Int) = i + 1
inc: (i: Int)Int
scala> (inc(_: Int)).hashCode
res15: Int = 1231799381
scala> (inc(_: Int)).hashCode
res16: Int = 2109839984
scala> (inc(_: Int)) == (inc(_: Int))
res17: Boolean = false
```
This seems leading to the comparison failure between `ScalaUDF`s created from Java UDF API, for example, in `Expression.semanticEquals`.
In case of Scala one, it seems already fine.
Both can be tested easily as below if any reviewer is more comfortable with Scala:
```scala
val df = Seq((1, 10), (2, 11), (3, 12)).toDF("x", "y")
val javaUDF = new UDF1[Int, Int] {
override def call(i: Int): Int = i + 1
}
// spark.udf.register("inc", javaUDF, IntegerType) // Uncomment this for Java API
// spark.udf.register("inc", (i: Int) => i + 1) // Uncomment this for Scala API
df.createOrReplaceTempView("tmp")
spark.sql("SELECT inc(y) FROM tmp GROUP BY inc(y)").show()
```
## How was this patch tested?
Unit test in `JavaUDFSuite.java` and `./dev/lint-java`.
Author: hyukjinkwon <gurwls223@gmail.com>
Closes#16553 from HyukjinKwon/SPARK-9435.
e576c1ed79