Revert "Upgrade Gradle to 5.2.1 (#1203)" (#1300)

diff --git a/gradle.properties b/gradle.properties
index a63d500..5926726 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -18,7 +18,7 @@
 version=1.4.0
 scalaSuffix=2.11
 
-gradleVersion=5.2.1
+gradleVersion=4.8
 
 org.gradle.jvmargs="-XX:MaxPermSize=512m"