Add Java toolchain

Author: dondonz

build.gradle

@@ -11,15 +11,12 @@ plugins {
     id "biz.aQute.bnd.builder" version "6.4.0"
 }
 
-if (JavaVersion.current() != JavaVersion.VERSION_1_8) {
-    def msg = String.format("This build must be run with java 1.8 - you are running %s - gradle finds the JDK via JAVA_HOME=%s",
-            JavaVersion.current(), System.getenv("JAVA_HOME"))
-    throw new GradleException(msg)
+java {
+    toolchain {
+        languageVersion = JavaLanguageVersion.of(11)
+    }
 }
 
-sourceCompatibility = 1.8
-targetCompatibility = 1.8
-
 def getDevelopmentVersion() {
     def output = new StringBuilder()
     def error = new StringBuilder()