java {
    toolchain {
        languageVersion = JavaLanguageVersion.of(7)
    }
}
// end::java-cross-compilation[]

tasks.withType(Test) {
    systemProperty('targetJavaVersion', project.findProperty('targetJavaVersion'))
}

tasks.register('checkJavadocOutput') {
    dependsOn javadoc
    def docsDir = java.docsDir
    doLast {

java {
    toolchain {
        languageVersion = JavaLanguageVersion.of(7)
    }
}
// end::java-cross-compilation[]

tasks.withType<Test>().configureEach {
    project.findProperty("targetJavaVersion")?.let { systemProperty("targetJavaVersion", it) }
}

tasks.register("checkJavadocOutput") {
    dependsOn(tasks.javadoc)
    val docsDir = java.docsDir
    doLast {

        Person person = new Person("");
        person.getName();
    }

    @Test
    public void testJavaVersion() {
        assertEquals(System.getProperty("java.version").substring(0, 3), System.getProperty("targetJavaVersion"));
    }

        Person person = new Person("");
        person.getName();
    }

    @Test
    public void testJavaVersion() {
        assertEquals(System.getProperty("java.version").substring(0, 3), System.getProperty("targetJavaVersion"));
    }