code: protected <I, T extends I> void registerExtendedBinder(Class<I> iface, T provider) {
          extendedBinders.put(iface, provider);
      }
docs: Register a custom, typesafe binder implementation which can be retrieved later
  @param iface The interface for the provider to be registered.
  @param provider The implementation.
  @param <I> The class to be registered
  @param <T> Implementation of the binder type, I.