fruit::Required doesn't work as expected in some cases

[poletti-marco]

For example, this doesn't compile and it should.

#include <fruit/fruit.h>
struct X {
  virtual void foo() = 0;
};
using XFactory = std::function<std::unique_ptr<X>()>;
struct Y {
  INJECT(Y(XFactory)) {}
};
fruit::Component<fruit::Required<XFactory>, Y> getYComponent() {
    return fruit::createComponent();
}

[poletti-marco]

This works now, closing.