}

    /**
     *
     */
    @Test
    public void testGetPrimitiveClass() {
        assertThat(ClassUtil.getPrimitiveClass(Integer.class), is(sameClass(int.class)));
        assertThat(ClassUtil.getPrimitiveClass(String.class), is(nullValue()));
        assertThat(ClassUtil.getPrimitiveClass(Byte.class), is(sameClass(byte.class)));
    }

    /**
     *
     */
    @Test

     * @param clazz
     *            The wrapper class. Must not be {@literal null}.
     * @return The primitive class if the argument is a wrapper class, otherwise {@literal null}.
     */
    public static Class<?> getPrimitiveClass(final Class<?> clazz) {
        assertArgumentNotNull("clazz", clazz);

        return wrapperToPrimitiveMap.get(clazz);
    }

    /**