When trying to compile a Java @FunctionalInterface having more than 1 non-abstract method a compilation error is raised.

However, when doing the same in Kotlin, no errors or warnings are raised, i.e. the following Kotlin interface compiles successfully:

@FunctionalInterface
interface Foo {
    fun foo()
    fun foo(params: Map<String, String>)
}

Is this the intended behaviour or a bug in the Kotlin compiler?

Please note that the generated bytecode for the above Kotlin snippet is equivalent to the following Java snippet (which – correctly – doesn't compile):

@FunctionalInterface
// metadata omitted
public interface Foo {
   void foo();
   void foo(@NotNull Map var1);
}