@Override
    public Set<Entry<K, V>> entrySet() {
        if (entrySet == null)
            entrySet = new EntrySet();
        return entrySet;
    }
Make a copy of the given map with the requisite deepness.
This default implementation does return new HashMap&lt;&gt;(original);
vespajlib/src/main/java/com/yahoo/collections/CopyOnWriteHashMap.java