Update Gradle wrapper to 3.5
diff --git a/build.gradle b/build.gradle
index 9e8205d..cbcbf72 100644
--- a/build.gradle
+++ b/build.gradle
@@ -204,6 +204,6 @@
 }
 
 task wrapper(type: Wrapper) {
-    gradleVersion = '3.1'
+    gradleVersion = '3.5'
     distributionType = Wrapper.DistributionType.ALL
 }
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