[Java] Upgrade to Gradle 4.1.

Author: mjpt777

build.gradle

@@ -612,6 +612,6 @@ task uploadToMavenCentral {
 }
 
 task wrapper(type: Wrapper) {
-    gradleVersion = '4.0.2'
+    gradleVersion = '4.1'
     distributionType = 'ALL'
 }

gradle/wrapper/gradle-wrapper.jar

@@ -1,6 +1,6 @@
-#Wed Aug 02 19:08:54 BST 2017
+#Wed Aug 16 21:16:52 BST 2017
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-4.0.2-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-4.1-all.zip