Upgrade to Gradle 5.6.2

This closes #1882.
diff --git a/lib/java/gradle/wrapper/gradle-wrapper.properties b/lib/java/gradle/wrapper/gradle-wrapper.properties
index 826c82f..7c4388a 100644
--- a/lib/java/gradle/wrapper/gradle-wrapper.properties
+++ b/lib/java/gradle/wrapper/gradle-wrapper.properties
@@ -1,5 +1,5 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
+distributionUrl=https\://services.gradle.org/distributions/gradle-5.6.2-bin.zip
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-5.1.1-bin.zip