public TypeK getk( TypeK key ) {
    return (TypeK)getk_impl(this,_kvs,key);
  }
Returns the Key to which the specified key is mapped, or {@code null}
 if this map contains no mapping for the key.
@throws NullPointerException if the specified key is null
jctools-core/src/main/java/org/jctools/maps/NonBlockingHashMap.java