[Java] Upgrade to Gradle 3.4.

Author: mjpt777

build.gradle

@@ -86,7 +86,7 @@ def projectPom = {
 }
 
 task wrapper(type: Wrapper) {
-    gradleVersion = '3.3'
+    gradleVersion = '3.4'
     distributionType = 'ALL'
 }
 

gradle/wrapper/gradle-wrapper.jar

@@ -1,6 +1,6 @@
-#Tue Jan 03 21:07:45 GMT 2017
+#Tue Feb 21 09:13:48 GMT 2017
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-3.3-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-3.4-all.zip