@Override
 public boolean compareAndSwap(String key, String oldValue, String newValue) {
   return errorHandler.wrapBooleanCall(delegate.cas(key, oldValue, newValue));
 }
 @Override
 public boolean compareAndSwap(byte[] key, byte[] oldValue, byte[] newValue) {
   return errorHandler.wrapBooleanCall(delegate.cas(key, oldValue, newValue));
 }