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

        return primitiveToWrapperMap.get(clazz);
    }

    /**

    }

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

    /**
     *
     */
    @Test