code: private List<Pair<Id, GuiceSupplier>> getSuppliers() {
          ImmutableList.Builder<Pair<Id, GuiceSupplier>> suppliersBuilder = ImmutableList.builder();
          for (Binding<GuiceRegistration> registrationBinding : injector.findBindingsByType(TypeLiteral.get(GuiceRegistration.class))) {
              Key<?> key = registrationBinding.getProvider().get().key();
              suppliersBuilder.add(newPair(key));
          }
          return suppliersBuilder.build();
      }
docs: enforce load all providers before register them