Kotlin Map with non null values
There is another method for getting not null value from map:
fun <K, V> Map<K, V>.getValue(key: K): V
throws NoSuchElementException - when the map doesn't contain a value for the specified key and no implicit default value was provided for that map.
but operator for get == map[] returns nullable.
operator fun <K, V> Map<out K, V>.get(key: K): V?
It is not about the implementation of Map (being it Kotlin or Java based). You are using a Map and a map may not have a key hence [] operator returns nullable type.