binder::resolve behavior inquiry

[xilef]

I am tracing the injector.create function until I reach this point in the code

  auto create_successful_impl__() const {
    auto&& dependency = binder::resolve<T, TName>((injector*)this);

How does resolve get TDefault even though it was not specified in the call?

  template <class T, class TName = no_name, class TDefault = dependency<scopes::deduce, aux::decay_t<T>>, class TDeps>
  static decltype(auto) resolve(TDeps* deps) noexcept {
    using dependency = dependency_concept<aux::decay_t<T>, TName>;

I am testing with a simple class with a simple call to create

class SingleClass {
public:
	SingleClass()
	{

	}

	~SingleClass()
	{

	}
};

...

auto injector2 = di::make_injector();
SingleClass test = injector2.create < SingleClass>();

I am seeing TDefault has a proper dependency

boost::ext::di::v1_2_0::core::dependency<
	boost::ext::di::v1_2_0::scopes::deduce,
	SingleClass,
	SingleClass,
	boost::ext::di::v1_2_0::no_name,
	void,
	boost::ext::di::v1_2_0::core::none>

Where did TDefault come from?