sample-java-gradle/build.gradle.kts

plugins {
    java
    application
}

java {
    toolchain {
        languageVersion.set(JavaLanguageVersion.of(11))
    }
}

application {
    mainClass.set("com.google.WebApp")
}

tasks.withType<Jar> {
    manifest {
        attributes["Main-Class"] = application.mainClass.get()
    }
}