[SPARK-17308] Improved the spark core code by replacing all pattern match on boolean value by if/else block.

## What changes were proposed in this pull request?
Improved the code quality of spark by replacing all pattern match on boolean value by if/else block.

## How was this patch tested?

By running the tests

Author: Shivansh <shiv4nsh@gmail.com>

Closes #14873 from shiv4nsh/SPARK-17308.

core/src/main/scala/org/apache/spark/deploy/Client.scala

@@ -124,11 +124,7 @@ private class ClientEndpoint(
     logInfo("... polling master for driver state")
     val statusResponse =
       activeMasterEndpoint.askWithRetry[DriverStatusResponse](RequestDriverStatus(driverId))
-    statusResponse.found match {
-      case false =>
-        logError(s"ERROR: Cluster master did not recognize $driverId")
-        System.exit(-1)
-      case true =>
+    if (statusResponse.found) {
       logInfo(s"State of $driverId is ${statusResponse.state.get}")
       // Worker node, if present
       (statusResponse.workerId, statusResponse.workerHostPort, statusResponse.state) match {
@@ -145,6 +141,9 @@ private class ClientEndpoint(
         case _ =>
           System.exit(0)
       }
+    } else {
+      logError(s"ERROR: Cluster master did not recognize $driverId")
+      System.exit(-1)
     }
   }
 

mllib/src/test/scala/org/apache/spark/mllib/clustering/KMeansSuite.scala

@@ -304,10 +304,9 @@ class KMeansSuite extends SparkFunSuite with MLlibTestSparkContext {
 
 object KMeansSuite extends SparkFunSuite {
   def createModel(dim: Int, k: Int, isSparse: Boolean): KMeansModel = {
-    val singlePoint = isSparse match {
-      case true =>
+    val singlePoint = if (isSparse) {
       Vectors.sparse(dim, Array.empty[Int], Array.empty[Double])
-      case _ =>
+    } else {
       Vectors.dense(Array.fill[Double](dim)(0.0))
     }
     new KMeansModel(Array.fill[Vector](k)(singlePoint))

project/SparkBuild.scala

@@ -212,9 +212,10 @@ object SparkBuild extends PomBuild {
     cachedFun(findFiles(scalaSource.in(config).value))
   }
 
-  private def findFiles(file: File): Set[File] = file.isDirectory match {
-    case true => file.listFiles().toSet.flatMap(findFiles) + file
-    case false => Set(file)
+  private def findFiles(file: File): Set[File] = if (file.isDirectory) {
+    file.listFiles().toSet.flatMap(findFiles) + file
+  } else {
+    Set(file)
   }
 
   def enableScalaStyle: Seq[sbt.Def.Setting[_]] = Seq(

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/trees/TreeNode.scala

@@ -103,9 +103,10 @@ abstract class TreeNode[BaseType <: TreeNode[BaseType]] extends Product {
    * Find the first [[TreeNode]] that satisfies the condition specified by `f`.
    * The condition is recursively applied to this node and all of its children (pre-order).
    */
-  def find(f: BaseType => Boolean): Option[BaseType] = f(this) match {
-    case true => Some(this)
-    case false => children.foldLeft(Option.empty[BaseType]) { (l, r) => l.orElse(r.find(f)) }
+  def find(f: BaseType => Boolean): Option[BaseType] = if (f(this)) {
+    Some(this)
+  } else {
+    children.foldLeft(Option.empty[BaseType]) { (l, r) => l.orElse(r.find(f)) }
   }
 
   /**

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/StringKeyHashMap.scala

@@ -22,9 +22,10 @@ package org.apache.spark.sql.catalyst.util
  * sensitive or insensitive.
  */
 object StringKeyHashMap {
-  def apply[T](caseSensitive: Boolean): StringKeyHashMap[T] = caseSensitive match {
-    case false => new StringKeyHashMap[T](_.toLowerCase)
-    case true => new StringKeyHashMap[T](identity)
+  def apply[T](caseSensitive: Boolean): StringKeyHashMap[T] = if (caseSensitive) {
+    new StringKeyHashMap[T](identity)
+  } else {
+    new StringKeyHashMap[T](_.toLowerCase)
   }
 }
 

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/analysis/AnalysisErrorSuite.scala

@@ -414,10 +414,9 @@ class AnalysisErrorSuite extends AnalysisTest {
             AttributeReference("a", dataType)(exprId = ExprId(2)),
             AttributeReference("b", IntegerType)(exprId = ExprId(1))))
 
-      shouldSuccess match {
-        case true =>
+      if (shouldSuccess) {
         assertAnalysisSuccess(plan, true)
-        case false =>
+      } else {
         assertAnalysisError(plan, "expression `a` cannot be used as a grouping expression" :: Nil)
       }
     }

streaming/src/main/scala/org/apache/spark/streaming/api/java/JavaPairDStream.scala

@@ -471,9 +471,10 @@ class JavaPairDStream[K, V](val dstream: DStream[(K, V)])(
       val list: JList[V] = values.asJava
       val scalaState: Optional[S] = JavaUtils.optionToOptional(state)
       val result: Optional[S] = in.apply(list, scalaState)
-      result.isPresent match {
-        case true => Some(result.get())
-        case _ => None
+      if (result.isPresent) {
+        Some(result.get())
+      } else {
+        None
       }
     }
     scalaFunc