Downgrade Gradle and Gradle Plugin to keep using Bintray Release, for now.

dependencies.gradle

@@ -5,7 +5,7 @@ ext.versions = [
     publishVersion    : '2.0.0-beta2',
     publishVersionCode: 213,
 
-    gradlePlugin      : '3.2.0',
+    gradlePlugin      : '3.1.4',
     spotlessPlugin    : '3.15.0',
     versionPlugin     : '0.20.0',
     bintrayPlugin     : '0.8.1',

gradle/wrapper/gradle-wrapper.properties

@@ -2,4 +2,4 @@ distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-4.8-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-4.4-bin.zip