BeanDesc bd = BeanDescFactory.getBeanDesc(Hoge.class);
        PropertyDesc pd = bd.getPropertyDesc("foo");
        assertThat(pd.isParameterized(), is(true));
        assertThat(pd.getElementClassOfCollection(), is(sameClass(String.class)));

        ParameterizedClassDesc pcd = pd.getParameterizedClassDesc();
        assertThat(pcd.getRawClass(), is(sameClass(List.class)));

    }

    @Override
    public ParameterizedClassDesc getParameterizedClassDesc() {
        return parameterizedClassDesc;
    }

    @Override
    public Class<?> getElementClassOfCollection(final int index) {
        assertArgumentArrayIndex("index", index, parameterTypes.length);

        if (!Collection.class.isAssignableFrom(parameterTypes[index]) || !isParameterized(index)) {

     *            the index of the parameter
     * @return the element type if the parameter type at the specified index is a parameterized {@link Collection}, otherwise {@literal null}
     */
    Class<?> getElementClassOfCollection(int index);

    /**
     * Returns the key type if the method's parameter type at the specified index is a parameterized {@link Map}.
     *
     * @param index

     *
     * @param index
     *            The index of the parameter
     * @return The element type if the parameter type is a parameterized {@link Collection}, otherwise {@literal null}
     */
    Class<?> getElementClassOfCollection(int index);

    /**
     * Returns the key type if the parameter type of the method is a parameterized {@link Map}.
     *
     * @param index
     *            The index of the parameter

     *
     * @return the element type if this field is a parameterized {@link Collection}, otherwise {@literal null}
     */
    Class<?> getElementClassOfCollection();

    /**
     * Returns the key type if this field is a parameterized {@link Map}.
     *
     * @return the key type if this field is a parameterized {@link Map}, otherwise {@literal null}
     */

     *
     * @return the element type if this property is a parameterized {@link Collection}, otherwise {@literal null}
     */
    Class<?> getElementClassOfCollection();

    /**
     * Returns the key type if this property is a parameterized {@link Map}.
     *
     * @return the key type if this property is a parameterized {@link Map}, otherwise {@literal null}

    }

    @Override
    public ParameterizedClassDesc getParameterizedClassDesc() {
        return parameterizedClassDesc;
    }

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

    @Test
    public void testList() throws Exception {
        final BeanDesc beanDesc = new BeanDescImpl(MyBean.class);
        final FieldDesc hoge = beanDesc.getFieldDesc("list");
        assertThat(hoge.getElementClassOfCollection(), is(sameClass(String.class)));
    }

    /**
     * @throws Exception
     */
    @Test
    public void testMap() throws Exception {

    }

    @Override
    public ParameterizedClassDesc getParameterizedClassDesc() {
        return parameterizedClassDesc;
    }

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