[SPARK-20714][SS] Fix match error when watermark is set with timeout = no...

[SPARK-20714][SS] Fix match error when watermark is set with timeout = no timeout / processing timeout

## What changes were proposed in this pull request?

When watermark is set, and timeout conf is NoTimeout or ProcessingTimeTimeout (both do not need the watermark), the query fails at runtime with the following exception.
```
MatchException: Some(org.apache.spark.sql.catalyst.expressions.GeneratedClass$SpecificPredicate1a9b798e) (of class scala.Some)
    org.apache.spark.sql.execution.streaming.FlatMapGroupsWithStateExec$$anonfun$doExecute$1.apply(FlatMapGroupsWithStateExec.scala:120)
    org.apache.spark.sql.execution.streaming.FlatMapGroupsWithStateExec$$anonfun$doExecute$1.apply(FlatMapGroupsWithStateExec.scala:116)
    org.apache.spark.sql.execution.streaming.state.package$StateStoreOps$$anonfun$1.apply(package.scala:70)
    org.apache.spark.sql.execution.streaming.state.package$StateStoreOps$$anonfun$1.apply(package.scala:65)
    org.apache.spark.sql.execution.streaming.state.StateStoreRDD.compute(StateStoreRDD.scala:64)
```

The match did not correctly handle cases where watermark was defined by the timeout was different from EventTimeTimeout.

## How was this patch tested?
New unit tests.

Author: Tathagata Das <tathagata.das1565@gmail.com>

Closes #17954 from tdas/SPARK-20714.

sql/core/src/main/scala/org/apache/spark/sql/execution/streaming/FlatMapGroupsWithStateExec.scala

@@ -120,7 +120,7 @@ case class FlatMapGroupsWithStateExec(
         val filteredIter = watermarkPredicateForData match {
           case Some(predicate) if timeoutConf == EventTimeTimeout =>
             iter.filter(row => !predicate.eval(row))
-          case None =>
+          case _ =>
             iter
         }
 

sql/core/src/test/scala/org/apache/spark/sql/streaming/FlatMapGroupsWithStateSuite.scala

@@ -589,7 +589,7 @@ class FlatMapGroupsWithStateSuite extends StateStoreMetricsTest with BeforeAndAf
     )
   }
 
-  test("flatMapGroupsWithState - streaming with event time timeout") {
+  test("flatMapGroupsWithState - streaming with event time timeout + watermark") {
     // Function to maintain the max event time
     // Returns the max event time in the state, or -1 if the state was removed by timeout
     val stateFunc = (
@@ -761,6 +761,44 @@ class FlatMapGroupsWithStateSuite extends StateStoreMetricsTest with BeforeAndAf
     assert(e.getMessage === "The output mode of function should be append or update")
   }
 
+  def testWithTimeout(timeoutConf: GroupStateTimeout): Unit = {
+    test("SPARK-20714: watermark does not fail query when timeout = " + timeoutConf) {
+      // Function to maintain running count up to 2, and then remove the count
+      // Returns the data and the count (-1 if count reached beyond 2 and state was just removed)
+      val stateFunc =
+      (key: String, values: Iterator[(String, Long)], state: GroupState[RunningCount]) => {
+        if (state.hasTimedOut) {
+          state.remove()
+          Iterator((key, "-1"))
+        } else {
+          val count = state.getOption.map(_.count).getOrElse(0L) + values.size
+          state.update(RunningCount(count))
+          state.setTimeoutDuration("10 seconds")
+          Iterator((key, count.toString))
+        }
+      }
+
+      val clock = new StreamManualClock
+      val inputData = MemoryStream[(String, Long)]
+      val result =
+        inputData.toDF().toDF("key", "time")
+          .selectExpr("key", "cast(time as timestamp) as timestamp")
+          .withWatermark("timestamp", "10 second")
+          .as[(String, Long)]
+          .groupByKey(x => x._1)
+          .flatMapGroupsWithState(Update, ProcessingTimeTimeout)(stateFunc)
+
+      testStream(result, Update)(
+        StartStream(ProcessingTime("1 second"), triggerClock = clock),
+        AddData(inputData, ("a", 1L)),
+        AdvanceManualClock(1 * 1000),
+        CheckLastBatch(("a", "1"))
+      )
+    }
+  }
+  testWithTimeout(NoTimeout)
+  testWithTimeout(ProcessingTimeTimeout)
+
   def testStateUpdateWithData(
       testName: String,
       stateUpdates: GroupState[Int] => Unit,