final BeanDesc bd = BeanDescFactory.getBeanDesc(Hoge.class);
        PropertyDesc pd = bd.getPropertyDesc("baz");
        assertThat(pd.isParameterized(), is(true));
        assertThat(pd.getKeyClassOfMap(), is(sameClass(String.class)));
        assertThat(pd.getValueClassOfMap(), is(sameClass(Date.class)));

        ParameterizedClassDesc pcd = pd.getParameterizedClassDesc();

        if (pcd == null) {
            return null;
        }
        return pcd.getRawClass();
    }

    @Override
    public Class<?> getKeyClassOfMap() {
        if (!Map.class.isAssignableFrom(propertyType) || !isParameterized()) {
            return null;
        }
        final ParameterizedClassDesc pcd = parameterizedClassDesc.getArguments()[0];