/** {@inheritDoc} */
@Override
@SuppressWarnings("unchecked")
public boolean addElement(EntryImpl<Object, ?> child) {
final K k = (K) child.getKey();
final V v = (V) child.getValue();
if (!this.delegate.keySet().contains(k) && !this.delegate.values().contains(v)) {
this.delegate.put(k, v);
return true;
}
return false;
}