@Override
 public void update(Client entity) {
   // TODO Auto-generated method stub
   if (cache != null) {
     if (cache.isKeyInCache(entity.getEmail())) {
       cache.acquireWriteLockOnKey(entity.getEmail());
       cache.remove(entity.getEmail());
       cache.put(new Element(entity.getEmail(), entity));
       cache.releaseWriteLockOnKey(entity.getEmail());
     } else cache.put(new Element(entity.getEmail(), entity));
   }
 }
 @Override
 public void put(Client entity) {
   // TODO Auto-generated method stub
   if (cache != null) cache.put(new Element(entity.getEmail(), entity));
 }