set JVM to 11

build.gradle.kts

@@ -1,3 +1,5 @@
+import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
+
 plugins {
     jacoco
 
@@ -17,6 +19,12 @@ repositories {
     jcenter()
 }
 
+tasks.withType<KotlinCompile> {
+    kotlinOptions {
+        jvmTarget = "11"
+    }
+}
+
 dependencies {
     implementation("org.jetbrains.kotlin:kotlin-stdlib-jdk8")
     implementation("org.jetbrains.kotlin:kotlin-reflect:1.3.31")