src/main/java/org/jivesoftware/smack/util/collections/AbstractReferenceMap.java
public Collection<V> values() {
        if (values == null) {
            values = new ReferenceValues<K, V>(this);
        }
        return values;
    }
public Collection<V> values() {
        if (values == null) {
            values = new ReferenceValues<K, V>(this);
        }
        return values;
    }
Returns a collection view of this map's values.

@return a set view of this map's values