Kotlin: How convert from Set to Map?

I have Set<FlagFilter> and I need to convert it to Map<Class<out FlagFilter>, FlagFilter>.

I tried doing it like this:

val result: Map<Class<out FlagFilter>, FlagFilter> =
     target
        .takeIf { !it.isEmpty() }
         ?.map { mapOf(it.javaClass to it) }
         ?: emptyMap<>()

but instead of a Map it turns out to be a List and I get a compilation error:

Type mismatch.
Required: Map<Class<out FlagFilter>, FlagFilter>
Found: List<Map<Class<FlagFilter>, FlagFilter>>

What am I doing wrong? As if there is not enough operation, but I do not understand yet which one

>Solution :

Just use associateBy extension function:

val result: Map<Class<out FlagFilter>, FlagFilter> =
    target.associateBy { it.javaClass }

Or if you want to fix your code, remove the excessive call of mapOf(). Just convert your Set to List of Pairs, and then call toMap() to create a map:

val result: Map<Class<out FlagFilter>, FlagFilter> =
    target.map { it.javaClass to it }.toMap()