a way to get actual parameter type

JavaTest.java

	@Test
	public void testJavaGeneric() {
		// have to use a empty `{ }`, so that the `getClass().getGenericSuperclass()` will return a `ParameterizedType` instance.
		List<Integer> list = new LinkedList<Integer>() {
		};
		// superclass contains the unerased info.
		Type supers = list.getClass().getGenericSuperclass();
		assertTrue(supers instanceof ParameterizedType);
		ParameterizedType paramType = (ParameterizedType) supers;

		Type[] actualTypes = paramType.getActualTypeArguments();
		assertEquals(1, actualTypes.length);
		assertEquals(Integer.class, actualTypes[0]);
	}