fastForEachNullable

inline fun <T> FastIntMap<T>.fastForEachNullable(callback: (key: Int, value: T?) -> Unit)
inline fun <T> FastStringMap<T>.fastForEachNullable(callback: (key: String, value: T?) -> Unit)
inline fun <K, V> FastIdentityMap<K, V>.fastForEachNullable(callback: (key: K, value: V?) -> Unit)