Fix scanSuperTypes function to return Object Class instead of generic types

[yuanjin5]

Fix scanSuperTypes function to return Object Class instead of generic types

Unit Test Code

@Test
void testReturn_LV1Map() throws Exception {
   Class<?> clazz = Level1Mapper.class;
   Method method = clazz.getMethod("selectMap");
   Type result = TypeParameterResolver.resolveReturnType(method, clazz);
   assertTrue(result instanceof ParameterizedType);
   ParameterizedType paramType = (ParameterizedType) result;
   assertEquals(Map.class, paramType.getRawType());
   assertEquals(2, paramType.getActualTypeArguments().length);
   assertEquals(String.class, paramType.getActualTypeArguments()[0]);
   assertEquals(Object.class, paramType.getActualTypeArguments()[1]);
}

Expected :class java.lang.Object
Actual: F

[coveralls]

coverage: 87.179% (+0.01%) from 87.168%
when pulling 8fb229e on yuanjin5:fixbug
into acc1086 on mybatis:master.

[harawata]

Thank you, @yuanjin5 !

Although this is technically correct, it should not affect real projects. i.e. Level2Mapper#selectMap() should be used instead of Level1Mapper#selectMap().