TypeVariable.getGenericDeclaration() doesn't return the type I expect

In the code below I expect name to be BlackBox, as this is the type of the complex field. But it returns Pair, which is the type of the other field, simple:

public class QuestionTest {
    abstract class BlackBox<TSimple, TComplex> {
        public TComplex complex;
        public TSimple simple;
    }

    abstract class Pair {
        public String one;
        public String two;
    }

    @Test
    public void Test() throws NoSuchFieldException {
        BlackBox<Integer, Pair> blackBox =
                new BlackBox<Integer, Pair>() {};

        blackBox.complex = new Pair() {};
        blackBox.complex.one = "Uno";
        blackBox.complex.two = "Duo";
        blackBox.simple = 3;

        Class cls = blackBox.getClass();

        Field field = cls.getField("complex");
        TypeVariable typeVariable = (TypeVariable) field.getGenericType();
        GenericDeclaration genDec = typeVariable.getGenericDeclaration();
        Class genCls = (Class) genDec;
        String name = genCls.getSimpleName();
        Assert.assertEquals("Pair", name); // Fails! name is "BlackBox"
    }
}

Where's is my mistake?