fixed build. I'm embarassed that I didn't notice the empty JAR file.

build.gradle

@@ -1,4 +1,15 @@
+buildscript {
+    ext.kotlin_version = '1.1.60'
+    repositories {
+        mavenCentral()
+    }
+    dependencies {
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
+    }
+}
+
 apply plugin: 'java'
+apply plugin: 'kotlin'
 apply plugin: 'maven'
 apply plugin: 'signing'
 apply plugin: 'jacoco'
@@ -12,6 +23,9 @@ repositories {
 }
 
 dependencies {
+    compile "org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version"
+    compile "org.jetbrains.kotlin:kotlin-reflect:$kotlin_version"
+
     testCompile group: 'junit', name: 'junit', version: '4.11'
 }
 

gradle/wrapper/gradle-wrapper.properties

@@ -1,6 +1,6 @@
-#Tue Sep 19 21:21:56 CEST 2017
+#Mon Nov 20 19:17:21 CET 2017
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-4.1-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-4.2-all.zip

gradlew

@@ -1,4 +1,4 @@
-#!/usr/bin/env bash
+#!/usr/bin/env sh
 
 ##############################################################################
 ##
@@ -33,11 +33,11 @@ DEFAULT_JVM_OPTS=""
 # Use the maximum available, or set MAX_FD != -1 to use that value.
 MAX_FD="maximum"
 
-warn ( ) {
+warn () {
     echo "$*"
 }
 
-die ( ) {
+die () {
     echo
     echo "$*"
     echo
@@ -154,16 +154,19 @@ if $cygwin ; then
     esac
 fi
 
-# Split up the JVM_OPTS And GRADLE_OPTS values into an array, following the shell quoting and substitution rules
-function splitJvmOpts() {
-    JVM_OPTS=("$@")
+# Escape application args
+save () {
+    for i do printf %s\\n "$i" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/' \\\\/" ; done
+    echo " "
 }
-eval splitJvmOpts $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS
-JVM_OPTS[${#JVM_OPTS[*]}]="-Dorg.gradle.appname=$APP_BASE_NAME"
+APP_ARGS=$(save "$@")
+
+# Collect all arguments for the java command, following the shell quoting and substitution rules
+eval set -- $DEFAULT_JVM_OPTS $JAVA_OPTS $GRADLE_OPTS "\"-Dorg.gradle.appname=$APP_BASE_NAME\"" -classpath "\"$CLASSPATH\"" org.gradle.wrapper.GradleWrapperMain "$APP_ARGS"
 
 # by default we should be in the correct project dir, but when run from Finder on Mac, the cwd is wrong
-if [[ "$(uname)" == "Darwin" ]] && [[ "$HOME" == "$PWD" ]]; then
+if [ "$(uname)" = "Darwin" ] && [ "$HOME" = "$PWD" ]; then
   cd "$(dirname "$0")"
 fi
 
-exec "$JAVACMD" "${JVM_OPTS[@]}" -classpath "$CLASSPATH" org.gradle.wrapper.GradleWrapperMain "$@"
+exec "$JAVACMD" "$@"