Por exemplo:

Java:

public class Foo {

    public int getSomething() {
        return 1;
    }

}

Kotlin:

class Bar : Foo() {

    // works
    override fun getSomething() = 2

    // doesn't work ('something' overrides nothing)
    // override val something = 2

}

Eu pensei queval something = 2 será transformado empublic int getSomething() { return 2; } no bytecode Java.