This is the current implementation in stdlib: ```p...

# stdlib

[dave08]

This is the current implementation in stdlib:

public inline fun <K, V> ConcurrentMap<K, V>.getOrPut(key: K, defaultValue: () -> V): V {
    // Do not use computeIfAbsent on JVM8 as it would change locking behavior
    return this.get(key)
            ?: defaultValue().let { default -> this.putIfAbsent(key, default) ?: default }
}

The problem is that if defaultValue returns null, putIfAbsent will crash with an NPE... is there a way to ensure that it should not be able to receive nulls?