src/main/java/org/jivesoftware/smack/util/collections/AbstractReferenceMap.java
public Set<Map.Entry<K, V>> entrySet() {
        if (entrySet == null) {
            entrySet = new ReferenceEntrySet<K, V>(this);
        }
        return entrySet;
    }
public Set<Map.Entry<K, V>> entrySet() {
        if (entrySet == null) {
            entrySet = new ReferenceEntrySet<K, V>(this);
        }
        return entrySet;
    }
Returns a set view of this map's entries. An iterator returned entry is
valid until <code>next()</code> is called again. The
<code>setValue()</code> method on the <code>toArray</code> entries has no
effect.

@return a set view of this map's entries