protected Object clone() {
        try {
            AbstractHashedMap cloned = (AbstractHashedMap) super.clone();
            cloned.data = new HashEntry[data.length];
            cloned.entrySet = null;
            cloned.keySet = null;
            cloned.values = null;
            cloned.modCount = 0;
            cloned.size = 0;
            cloned.init();
            cloned.putAll(this);
            return cloned;

        } catch (CloneNotSupportedException ex) {
            return null;  // should never happen
        }
    }
Clones the map without cloning the keys or values.
<p/>
To implement <code>clone()</code>, a subclass must implement the
<code>Cloneable</code> interface and make this method public.

@return a shallow clone
jphp-runtime/src/php/runtime/common/collections/map/AbstractHashedMap.java