How to restrict kotlin from using java api which is announced above jdk1.6 - kotlin

Question

My compilation environment is jdk1.8 and runtime environment is jdk1.6. java plugin of gradle has sourceCompatibility attribute. It is valid for java project.
For example: when sourceCompatibility=1.6, compiler will report error if I use the api such as Paths which is from jdk1.7.
but sourceCompatibility attribute doesn't work for kotlin project. I understand it is out of java plugin's scope. But I am strange whether kotlin plugin of gradle hasn't similar attribute. (jvmTarget attribute is 1.6 by default, it does't prevent me from using jdk1.7 api)
=== my code ===
kotlin code:
fun main(args: Array<String>) {
val pp = Paths.get("/tmp")
... ...
}
I want kotlin's compiler to report errors, but the compilation is successful,
parent build.gradle:
buildscript {
repositories {
jcenter()
}
dependencies {
classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:1.1.0"
}
}
subprojects {
apply plugin: "java"
compileJava.sourceCompatibility=1.6
compileJava.targetCompatibility=1.6
compileJava.options.encoding = 'UTF-8'
// For ubuntu
compileJava.options.bootClasspath = '/usr/lib/jvm/java-6-oracle/jre/lib/rt.jar'
}
child kotlin project build.gradle:
apply plugin: 'application'
apply plugin: 'kotlin'
mainClassName = 'net.cat.ApplictionKt'
version='1.0'
jar {
manifest {
attributes 'Implementation-Title': 'xxxx',
'Implementation-Version': version,
'Main-Class': mainClassName
}
}
dependencies {
compile "org.jetbrains.kotlin:kotlin-stdlib:1.1.0"
compile "org.jetbrains.kotlin:kotlin-reflect:1.1.0"
... ...
}

Answer 1

You can set the jdkHome property of the Kotlin compiler:
compileKotlin {
kotlinOptions {
jdkHome = '[path to 1.6 JDK]'
}
}