bson/src/main/org/bson/util/CopyOnWriteMap.java
public static <K, V> CopyOnWriteMap<K, V> newHashMap(final Map<? extends K, ? extends V> map) {
        Builder<K, V> builder = builder();
        return builder.addAll(map).newHashMap();
    }
public static <K, V> CopyOnWriteMap<K, V> newHashMap(final Map<? extends K, ? extends V> map) {
        Builder<K, V> builder = builder();
        return builder.addAll(map).newHashMap();
    }
<p> Creates a new {@link CopyOnWriteMap} with an underlying {@link HashMap} using the supplied map as the initial values. </p>

<p>This map has {@link View.Type#STABLE stable} views.</p>