Upgrade to Gradle 4.2 (and Netty 4.1.16)

Issue: SPR-15985

Author: jhoeller

build.gradle

@@ -47,16 +47,16 @@ configure(allprojects) { project ->
 	ext.hsqldbVersion        = "2.4.0"
 	ext.jackson2Version      = "2.9.1"
 	ext.jettyVersion         = "9.4.7.v20170914"
-	ext.junitJupiterVersion  = '5.0.0'
-	ext.junitPlatformVersion = '1.0.0'
+	ext.junitJupiterVersion  = "5.0.0"
+	ext.junitPlatformVersion = "1.0.0"
 	ext.junitVintageVersion  = "4.12.0"
-	ext.kotlinVersion        = '1.1.51'
-	ext.log4jVersion         = '2.9.1'
-	ext.nettyVersion         = "4.1.15.Final"
+	ext.kotlinVersion        = "1.1.51"
+	ext.log4jVersion         = "2.9.1"
+	ext.nettyVersion         = "4.1.16.Final"
 	ext.reactorVersion       = "Bismuth-RELEASE"
-	ext.rxjavaVersion        = '1.3.2'
-	ext.rxjavaAdapterVersion = '1.2.1'
-	ext.rxjava2Version       = '2.1.4'
+	ext.rxjavaVersion        = "1.3.2"
+	ext.rxjavaAdapterVersion = "1.2.1"
+	ext.rxjava2Version       = "2.1.4"
 	ext.slf4jVersion         = "1.7.25"
 	ext.tiles3Version        = "3.0.7"
 	ext.tomcatVersion        = "8.5.21"
@@ -268,7 +268,7 @@ configure(rootProject) {
 
 	task wrapper(type: Wrapper) {
 		description = "Generates gradlew[.bat] scripts"
-		gradleVersion = '4.1'
+		gradleVersion = '4.2'
 
 		doLast() {
 			def gradleOpts = "-XX:MaxMetaspaceSize=1024m -Xmx1024m"

gradle/wrapper/gradle-wrapper.jar

@@ -2,4 +2,4 @@ distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-4.1-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-4.2-bin.zip