``` val result: List<FooBar> = foos.flatMap ...

# codereview

[raulraja]

val result: List<FooBar> = foos.flatMap { foo ->
        if (foo.bars.isNotEmpty()) {
            foo.bars.map { bar ->
                FooBar(foo, bar)
            }
        } else listOf(FooBar(foo, null))
    }