public boolean hasSpec(String id) {
   for (BackendSpec<B> backendSpec : backendSpecs) {
     if (id.equals(backendSpec.getId())) {
       return true;
     }
   }
   return false;
 }
 public BackendSpec<B> loadSpec(String id) throws BackendSpecNotFoundException {
   for (BackendSpec<B> backendSpec : backendSpecs) {
     if (id.equals(backendSpec.getId())) {
       return backendSpec;
     }
   }
   throw new BackendSpecNotFoundException(id);
 }