Updated to Java 11

build.gradle

@@ -6,6 +6,11 @@ plugins {
 group 'org.hmcore'
 version '1.0-SNAPSHOT'
 
+java {
+    sourceCompatibility = JavaVersion.VERSION_11
+    targetCompatibility = JavaVersion.VERSION_11
+}
+
 repositories {
     mavenCentral()
 }