Compile Kotlin tasks using JVM 1.8

config/spring-security-config.gradle

@@ -1,3 +1,5 @@
+import org.jetbrains.kotlin.gradle.tasks.KotlinCompile
+
 apply plugin: 'io.spring.convention.spring-module'
 apply plugin: 'trang'
 apply plugin: 'kotlin'
@@ -85,7 +87,7 @@ rncToXsd {
 	xslFile = new File(rncDir, 'spring-security.xsl')
 }
 
-compileKotlin {
+tasks.withType(KotlinCompile).configureEach {
 	kotlinOptions {
 		jvmTarget = "1.8"
 		freeCompilerArgs = ["-Xjsr305=strict"]