static void unregister(Object lhs, Object rhs) {
        Set<Pair<IDKey, IDKey>> registry = getRegistry();
        if (registry != null) {
            Pair<IDKey, IDKey> pair = getRegisterPair(lhs, rhs);
            registry.remove(pair);
            synchronized (EqualsBuilder.class) {
                //read again
                registry = getRegistry();
                if (registry != null && registry.isEmpty()) {
                    REGISTRY.remove();
                }
            }
        }
    }
<p>
Unregisters the given object pair.
</p>

<p>
Used by the reflection methods to avoid infinite loops.

@param lhs <code>this</code> object to unregister
@param rhs the other object to unregister
@since 3.0
android/android_framework/base/src/main/java/lang3/builder/EqualsBuilder.java