Downgrade jline since newest version breaks tab completion

Author: graemerocher

build.gradle

@@ -38,7 +38,7 @@ ext {
     groovyVersion = System.getenv('CI_GROOVY_VERSION') ?: "2.4.7"
     ivyVersion = "2.3.0"
     jansiVersion = "1.14"
-    jlineVersion = "2.14.2"
+    jlineVersion = "2.12"
     jnaVersion = "4.2.2"
     slf4jVersion = "1.7.22"
     reactorCoreVersion = '2.0.8.RELEASE'