Wildcards types support

[fborriello]

Description
As per today, the library is able to transform all the elements inside a Collection or a Map if their type is specified in the generic type, so it's not able to transform object described as following:

private final Collection<? super Object> collection;
private final Collection collection;

private final Map map;
private final Map<?, ?> map;
private final Map<? super Object, ? super Object> map;

The purpose of this issue is to make the library able to transform such objects.

[fborriello]

Feature available on the release: 1.6.4 for jdk11 and 1.6.3.2-jdk8 for jdk8