@Override
 public <T> T post(Entity<?> entity, Class<T> cls) {
   return sync.post(entity, cls);
 }
 @Override
 public <T> T post(Entity<?> entity, GenericType<T> type) {
   return sync.post(entity, type);
 }
 @Override
 public Response post(Entity<?> entity) {
   return sync.post(entity);
 }