## What changes were proposed in this pull request?
This PR fixes the Scala-2.12 build error due to ambiguity in `foreachBatch` test cases.
- https://amplab.cs.berkeley.edu/jenkins/view/Spark%20QA%20Test%20(Dashboard)/job/spark-master-test-maven-hadoop-2.7-ubuntu-scala-2.12/428/console
```scala
[error] /home/jenkins/workspace/spark-master-test-maven-hadoop-2.7-ubuntu-scala-2.12/sql/core/src/test/scala/org/apache/spark/sql/execution/streaming/sources/ForeachBatchSinkSuite.scala:102: ambiguous reference to overloaded definition,
[error] both method foreachBatch in class DataStreamWriter of type (function: org.apache.spark.api.java.function.VoidFunction2[org.apache.spark.sql.Dataset[Int],Long])org.apache.spark.sql.streaming.DataStreamWriter[Int]
[error] and method foreachBatch in class DataStreamWriter of type (function: (org.apache.spark.sql.Dataset[Int], Long) => Unit)org.apache.spark.sql.streaming.DataStreamWriter[Int]
[error] match argument types ((org.apache.spark.sql.Dataset[Int], Any) => Unit)
[error] ds.writeStream.foreachBatch((_, _) => {}).trigger(Trigger.Continuous("1 second")).start()
[error] ^
[error] /home/jenkins/workspace/spark-master-test-maven-hadoop-2.7-ubuntu-scala-2.12/sql/core/src/test/scala/org/apache/spark/sql/execution/streaming/sources/ForeachBatchSinkSuite.scala:106: ambiguous reference to overloaded definition,
[error] both method foreachBatch in class DataStreamWriter of type (function: org.apache.spark.api.java.function.VoidFunction2[org.apache.spark.sql.Dataset[Int],Long])org.apache.spark.sql.streaming.DataStreamWriter[Int]
[error] and method foreachBatch in class DataStreamWriter of type (function: (org.apache.spark.sql.Dataset[Int], Long) => Unit)org.apache.spark.sql.streaming.DataStreamWriter[Int]
[error] match argument types ((org.apache.spark.sql.Dataset[Int], Any) => Unit)
[error] ds.writeStream.foreachBatch((_, _) => {}).partitionBy("value").start()
[error] ^
```
## How was this patch tested?
Manual.
Since this failure occurs in Scala-2.12 profile and test cases, Jenkins will not test this. We need to build with Scala-2.12 and run the tests.
Closes#22649 from dongjoon-hyun/SPARK-SCALA212.
Authored-by: Dongjoon Hyun <dongjoon@apache.org>
Signed-off-by: Dongjoon Hyun <dongjoon@apache.org>
9cbf105ab1