@Test
public void getComponentType() throws Exception {

    Field f1 = BaseClass.class.getField("f1");
    Field f5 = ConcreteClass.class.getField("f5");
    assertNull(ReflectionUtil.getComponentType(f1.getGenericType()));
    assertEquals(Long.class, ReflectionUtil.getComponentType(f5.getGenericType()));
}